Fair Value Measurements - Financial Assets and Liabilities, Recurring (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Assets
Deferred compensation plan	$ 16,962	$ 14,699
Derivative instruments	62,808	60,105
Liabilities
Deferred compensation plan	28,345	25,780
Recurring basis
Assets
Deferred compensation plan	16,962	14,699
Derivative instruments	62,808	60,105
Total assets	79,770	74,804
Liabilities
Deferred compensation plan	28,345	25,780
Derivative instruments	1,614	2,440
Total liabilities	29,959	28,220
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring basis
Assets
Deferred compensation plan	16,962	14,699
Derivative instruments	0	0
Total assets	16,962	14,699
Liabilities
Deferred compensation plan	28,345	25,780
Derivative instruments	0	0
Total liabilities	28,345	25,780
Significant Other Observable Inputs (Level 2) | Recurring basis
Assets
Deferred compensation plan	0	0
Derivative instruments	48,571	35,689
Total assets	48,571	35,689
Liabilities
Deferred compensation plan	0	0
Derivative instruments	0	0
Total liabilities	0	0
Significant Unobservable Inputs (Level 3) | Recurring basis
Assets
Deferred compensation plan	0	0
Derivative instruments	14,237	24,416
Total assets	14,237	24,416
Liabilities
Deferred compensation plan	0	0
Derivative instruments	1,614	2,440
Total liabilities	$ 1,614	$ 2,440