Leases - Lease Balances within the Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets:
Operating lease right-of-use assets	$ 19,890
Liabilities:
Other accrued liabilities	4,501	$ 0
Long-term operating lease obligations	15,580
Total lease liabilities	$ 20,081