Employee Benefit Plans - Changes Recognized in OCI (Details) - Defined benefit plans - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial gain/(loss)		$ (9,379)	$ 1,026	$ (75,527)
Amortization of actuarial loss		(4,406)	(4,617)	(2,861)
Curtailments	$ 1,100	0	46,793	0
Total		$ (4,973)	$ 52,436	$ (72,666)