Leases - Operating Leases Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating leases
Operating lease right-of-use assets	$ 22,225	$ 21,300	$ 0
Liabilities [Abstract]
Other current liabilities	4,890
Operating lease liabilities	18,529		$ 0
Total operating lease liabilities	$ 23,419	$ 22,400
Weighted average remaining lease term, operating leases	6 years 30 days
Weighted average discount rate, operating leases	5.90%