Employee Benefit Plans - Components of Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	$ 5,720,000	$ 5,113,000	$ 16,978,000	$ 17,803,000
Allocated to discontinued operations	0	0	0	(1,096,000)
Net periodic benefit cost — continuing operations	5,720,000	5,113,000	16,978,000	16,707,000
Defined contribution plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	2,073,000	2,094,000	6,347,000	7,805,000
Multi-employer plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	42,000	43,000	127,000	140,000
Defined benefit plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost	6,839,000	8,169,000	20,379,000	22,797,000
Expected return on plan assets, net of expenses	(4,616,000)	(6,625,000)	(13,812,000)	(18,334,000)
Amortization of actuarial loss	1,102,000	1,179,000	3,097,000	3,515,000
Defined Benefit Plan, Curtailments	0	0	0	1,080,000
Total for defined benefit plans	3,325,000	2,723,000	9,664,000	9,058,000
SERPs
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic benefit cost	$ 280,000	$ 253,000	$ 840,000	$ 800,000