| Schedule of recurring and nonrecurring fair value measurements | 
  
    |   | 
  | 
    Fair
    Value | 
  | 
  | 
    Level
    1 | 
  | 
  | 
    Level
    2 | 
  | 
  | 
    Level
    3 | 
  | 
 
  
    | Assets: | 
  | 
      | 
  | 
  | 
      | 
  | 
  | 
      | 
  | 
  | 
      | 
  | 
 
  
    | Derivative
    financial instruments | 
  | 
    $ | 
19,498 | 
  | 
  | 
    $ | 
19,498 | 
  | 
  | 
    $ | 
—  | 
  | 
  | 
    $ | 
—  | 
  | 
 
  
    | Long-lived
    assets held-for-sale | 
  | 
      | 
1,000 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
1,000 | 
  | 
 
  
    |   | 
  | 
    $ | 
20,498 | 
  | 
  | 
    $ | 
19,498 | 
  | 
  | 
    $ | 
—  | 
  | 
  | 
    $ | 
1,000 | 
  | 
 
  
    | Liabilities: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
  
    |   | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
  
    | Derivative financial instruments | 
  | 
    $ | 
(27,487 | 
) | 
  | 
    $ | 
(27,487 | 
) | 
  | 
    $ | 
—  | 
  | 
  | 
    $ | 
—  | 
  | 
 
   
  
  
    |   | 
  | 
    Fair
    Value | 
  | 
  | 
    Level
    1 | 
  | 
  | 
    Level
    2 | 
  | 
  | 
    Level
    3 | 
  | 
  | 
    Benefit
    Plan  Percentage  Allocation | 
  | 
 
  
    | Assets: | 
  | 
      | 
  | 
  | 
      | 
  | 
  | 
      | 
  | 
  | 
      | 
  | 
  | 
      | 
  | 
 
  
    | Derivative
    financial instruments | 
  | 
    $ | 
15,839 | 
  | 
  | 
    $ | 
15,839 | 
  | 
  | 
    $ | 
—  | 
  | 
  | 
    $ | 
—  | 
  | 
  | 
      | 
  | 
  | 
 
  
    | Long-lived assets held-for-sale | 
  | 
      | 
1,000 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
1,000 | 
  | 
  | 
      | 
  | 
  | 
 
  
    | Defined benefit plan
    assets(1) | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
  
    | (pooled separate accounts): | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
  
    | Large U.S. Equity(2) | 
  | 
      | 
5,612 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
5,612 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
28 | 
% | 
 
  
    | Small/Mid U.S. Equity(3) | 
  | 
      | 
3,684 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
3,684 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
18 | 
% | 
 
  
    | International Equity(4) | 
  | 
      | 
2,909 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
2,909 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
15 | 
% | 
 
  
    | Fixed Income(5) | 
  | 
      | 
7,782 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
7,782 | 
  | 
  | 
      | 
—  | 
  | 
  | 
      | 
39 | 
% | 
 
  
    |   | 
  | 
    $ | 
36,826 | 
  | 
  | 
    $ | 
15,839 | 
  | 
  | 
    $ | 
19,987 | 
  | 
  | 
    $ | 
1,000 | 
  | 
  | 
      | 
  | 
  | 
 
  
    |   | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
  
    | Liabilities: | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
  | 
      | 
  | 
  | 
 
  
    | Derivative financial instruments | 
  | 
    $ | 
(13,582 | 
) | 
  | 
    $ | 
(13,582 | 
) | 
  | 
    $ | 
—  | 
  | 
  | 
    $ | 
—  | 
  | 
  | 
      | 
  | 
  | 
 
   
  
| (1) | 
Included in other assets in the consolidated balance sheets. | 
  
| (2) | 
This category includes investments in funds comprised of equity securities of large U.S. companies. The funds are valued using the net asset value method in which an average of the market prices for the underlying investments is used to value the fund. | 
  
| (3) | 
This category includes investments in funds comprised of equity securities of small- and medium-sized U.S. companies. The funds are valued using the net asset value method in which an average of the market prices for the underlying investments is used to value the fund. | 
  
| (4) | 
This category includes investments in funds comprised of equity securities of foreign companies including emerging markets. The funds are valued using the net asset value method in which an average of the market prices for the underlying investments is used to value the fund. | 
  
| (5) | 
This category includes investments in funds comprised of U.S. and foreign investment-grade fixed income securities, high-yield fixed income securities that are rated below investment-grade, U.S. treasury securities, mortgage-backed securities, and other asset-backed securities. The funds are valued using the net asset value method in which an average of the market prices for the underlying investments is used to value the fund. | 
  
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