Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements
Right-of-use asset	$ 4,020
Right-of-use liability	$ 4,069
Accounting Standards Update 2016-02 "Leases" | Adjustment
New Accounting Pronouncements
Right-of-use asset		$ 3,900
Right-of-use liability		$ 3,900