Summary of Significant Accounting Policies - Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Adoption of new accounting pronouncements
Lease, Practical Expedients, Package [true false]	true
Operating lease right-of-use assets	$ 10,580
Operating lease liabilities	13,935
Retained earnings	$ 181,167		$ 172,378
Accounting Standards Update 2016-02 | Adjustments.
Adoption of new accounting pronouncements
Operating lease right-of-use assets		$ 9,200
Operating lease liabilities		11,000
Retained earnings		$ 0