Significant Accounting Policies - Leases (Details) $ in Thousands	Dec. 31, 2019 USD ($) asset	Mar. 31, 2019 USD ($) asset	Jan. 01, 2019 USD ($)
Accounting Policies [Abstract]
Operating lease right-of-use assets	$ 27,532	$ 30,000	$ 30,000
Operating lease liability	$ 29,100	$ 31,000	$ 31,000
Operating lease, number of assets derecognized | asset	1	1
Operating lease liability, derecognized	$ 29,000	$ 29,000