Employee Benefit Plans - Components of Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	$ 4,657	$ 5,468
Defined benefit plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	21	17
Interest cost	6,278	5,976
Expected return on plan assets, net of expenses	(5,859)	(5,371)
Amortization of actuarial loss	642	1,061
Total for defined benefit plans	1,082	1,683
Multi-employer plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	119	120
SERP
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	296	286
Defined contribution plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	$ 3,160	$ 3,379