Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Amortization of:
Contribution to pension plans	$ 20,200
Estimated total contributions	80,000
Pension Benefits [Member]
Amortization of:
Net periodic benefit cost/(credit)	12,842	$ 10,518
Postretirement Benefits [Member]
Amortization of:
Net periodic benefit cost/(credit)	(241)	(279)
Company Administered Plan [Member] | Pension Benefits [Member]
Components of net periodic benefit cost
Service cost	3,400	3,627
Interest cost	22,240	21,887
Expected return on plan assets	(23,085)	(24,900)
Amortization of:
Net actuarial loss/(gain)	7,965	7,808
Prior service credit	0	(76)
Net periodic benefit cost/(credit)	10,520	8,346
Company Administered Plan [Member] | Pension Benefits U.S. [Member]
Amortization of:
Net periodic benefit cost/(credit)	11,175	8,892
Company Administered Plan [Member] | Pension Benefits Non-U.S. [Member]
Amortization of:
Net periodic benefit cost/(credit)	(655)	(546)
Company Administered Plan [Member] | Postretirement Benefits [Member]
Components of net periodic benefit cost
Service cost	69	111
Interest cost	232	284
Expected return on plan assets	0	0
Amortization of:
Net actuarial loss/(gain)	(484)	(196)
Prior service credit	(58)	(478)
Net periodic benefit cost/(credit)	(241)	(279)
Company Administered Plan [Member] | Postretirement Benefits U.S [Member]
Amortization of:
Net periodic benefit cost/(credit)	(340)	(415)
Company Administered Plan [Member] | Postretirement Benefits Non-U.S [Member]
Amortization of:
Net periodic benefit cost/(credit)	99	136
Union Administered Plan [Member] | Pension Benefits [Member]
Amortization of:
Net periodic benefit cost/(credit)	2,322	2,172
Union Administered Plan [Member] | Postretirement Benefits [Member]
Amortization of:
Net periodic benefit cost/(credit)	$ 0	$ 0