Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Amortization of:
Contribution to pension plans			$ 7,200
Estimated total contributions	$ 23,000		23,000
One-time non-cash charge		$ 7,700
Pension and other postretirement benefit plans, accumulated other comprehensive income (loss), net Transition Assets (Obligations), before Tax		12,800		$ 12,800
Pension Benefits
Amortization of:
Net pension expense	12,550	21,177	25,907	34,018
Company Administered Plan | Pension Benefits
Components of net periodic benefit cost
Service cost	3,017	3,005	6,266	6,405
Interest cost	21,426	27,093	42,915	49,332
Expected return on plan assets	(22,712)	(22,667)	(45,190)	(45,752)
Amortization of:
Net actuarial loss	8,077	8,600	16,527	16,565
Prior service cost	121	2,740	266	2,740
Net pension expense	9,929	18,771	20,784	29,290
Company Administered Plan | U.S. | Pension Benefits
Amortization of:
Net pension expense	10,547	19,263	21,858	30,437
Company Administered Plan | Non-U.S. | Pension Benefits
Amortization of:
Net pension expense	(618)	(492)	(1,074)	(1,147)
Union Administered Plan | Pension Benefits
Amortization of:
Net pension expense	$ 2,621	$ 2,406	$ 5,123	$ 4,728