Employee Benefit Plans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Settlement expense				$ 8,168
Other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Estimated other postretirement benefits to be paid in 2019					$ 400
Benefits paid			$ 200
Settlement expense	$ 0	$ 0	$ 0	$ 0