Fair Value Measurements - Financial Assets and Liabilities, Recurring (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets
Deferred compensation plan	$ 13,765	$ 12,587
Derivative instruments	13,880	2,991
Liabilities
Deferred compensation plan	26,199	24,169
Derivative instruments	2,688	40,259
Recurring basis
Assets
Deferred compensation plan	13,765	12,587
Derivative instruments	13,880	2,991
Total assets	27,645	15,578
Liabilities
Deferred compensation plan	26,199	24,169
Derivative instruments	3,638	40,259
Total liabilities	29,837	64,428
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring basis
Assets
Deferred compensation plan	13,765	12,587
Derivative instruments	0	0
Total assets	13,765	12,587
Liabilities
Deferred compensation plan	26,199	24,169
Derivative instruments	0	0
Total liabilities	26,199	24,169
Significant Other Observable Inputs (Level 2) | Recurring basis
Assets
Deferred compensation plan	0	0
Derivative instruments	0	0
Total assets	0	0
Liabilities
Deferred compensation plan	0	0
Derivative instruments	1,111	21,400
Total liabilities	1,111	21,400
Significant Unobservable Inputs (Level 3) | Recurring basis
Assets
Deferred compensation plan	0	0
Derivative instruments	13,880	2,991
Total assets	13,880	2,991
Liabilities
Deferred compensation plan	0	0
Derivative instruments	2,527	18,859
Total liabilities	$ 2,527	$ 18,859