Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Retirement Benefits [Abstract]
Interest cost	$ 1,813	$ 1,685	$ 5,439	$ 5,055
Expected return on plan assets	(1,111)	(1,524)	(3,333)	(4,571)
Recognized actuarial loss	732	689	2,197	2,068
Net periodic benefit cost	1,434	$ 850	4,303	$ 2,552
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions to qualified pension plan			2,200
Restoration Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	$ 400		$ 1,300