Employee Benefit Plans - Components of Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 28,561	$ 23,548	$ 22,765
Pension and Other Postretirement Benefit Expense, Discontinued Operations	(543)	(687)	(652)
Pension and Other Postretirement Benefit Expense, Continuing Operations	28,018	22,861	22,113
Multi-employer plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	190	253	168
Defined benefit plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	23,836	25,966	27,359
Expected return on plan assets, net of expenses	(22,232)	(17,439)	(18,466)
Amortization of actuarial loss	3,527	4,424	4,406
Settlement losses	11,713	0	0
Total for defined benefit plans	16,844	12,951	13,299
SERPs
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	746	869
Settlement losses	1,800
Net periodic benefit cost	2,908	1,161	1,033
Defined Contribution Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 8,619	$ 9,183	$ 8,265