Employee Benefit Plans (Details) - Net Periodic Benefit Pension Expense - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of net periodic benefit cost:
Interest cost	$ 1,635	$ 2,334	$ 2,346
Expected return on plan assets	(4,057)	(4,333)	(4,931)
Recognized net actuarial loss	571	367	249
Amortization of prior service cost	0	0	0
Recognized settlement loss	1,338	2,254	1,377
Net periodic (income) cost	(513)	622	(959)
Other changes in plan assets and benefit obligations recognized as a charge to other comprehensive (loss) income:
Net loss for the period	(3,911)	(9,191)	(10,752)
Amortization of net loss	1,909	2,621	1,625
Total unrealized loss	(2,002)	(6,570)	(9,127)
Total recognized in net periodic pension cost and other comprehensive (loss) income	$ (1,489)	$ (7,192)	$ (8,168)
Weighted-average assumptions used to determine the net periodic cost:
Discount rate	3.99%	3.60%	4.30%
Expected return on plan assets	6.50%	6.50%	7.25%