Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2015
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,922	$ 2,376	$ 6,439	$ 6,917
Expected return on plan assets	(2,699)	(2,906)	(8,146)	(9,067)
Pension settlement	(197)	(613)	(626)	(1,984)
Amortization of prior service costs (credits)	4	0	4		$ 0
Net benefit credit	(970)	(1,143)	(2,329)	(4,134)
Other postretirement benefits plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	120	140	360	419
Interest cost	876	918	2,629	2,755
Amortization of other actuarial losses (gains)	(2,236)	0	(2,236)	0
Net benefit credit	$ (1,240)	$ 1,058	$ 753	$ 3,174