Lease Commitments - Operating Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases, Operating [Abstract]
Operating lease cost	$ 4,699
Short-term lease cost	830
Variable lease cost	591
Total lease cost	$ 6,120
Operating lease expense		$ 4,039	$ 3,833