Employee Benefit Plans - Components of Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Total for defined benefit plans		$ 45,000
Net periodic benefit cost	$ 69,063	22,132	$ 20,623
Pension and Other Postretirement Benefit Expense, Discontinued Operations	(482)	(8,985)	(5,532)
Pension and Other Postretirement Benefit Expense, Continuing Operations	68,581	13,147	15,091
Defined benefit plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	0	85	79
Interest cost	30,477	25,539	23,732
Expected return on plan assets, net of expenses	(24,320)	(23,481)	(21,501)
Amortization of actuarial loss	4,617	2,861	4,192
Curtailments/Settlement losses	46,793	0	0
Total for defined benefit plans	57,567	5,004	6,502
Multi-employer plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	180	393	407
Withdrawal from GCIU multi-employer plan
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	351	4,100	0
SERP
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	0	0
Interest cost	747	638
Net periodic benefit cost	1,107	896	2,335
Defined contribution plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	$ 9,858	$ 11,739	$ 11,379