Leases and Commitments - Operating Lease Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leased Assets [Line Items]
Operating leases, rent expense	$ 12,426	$ 11,792	$ 9,444
Equipment Rent
Operating Leased Assets [Line Items]
Operating leases, rent expense	10,840	10,173	7,443
Building And Office Rents
Operating Leased Assets [Line Items]
Operating leases, rent expense	$ 1,586	$ 1,619	$ 2,001