Significant Accounting Policies - New Accounting Guidance (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total equity	$ 1,223,785	$ 1,144,557	$ 703,657	$ 691,111
Total Stockholders' Equity
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total equity	$ 1,022,875	951,731	$ 592,020	645,935
Impact of ASC 326 adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total equity		2,254		(9,908)
Impact of ASC 326 adoption | Total Stockholders' Equity
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total equity		$ 2,254		$ (9,908)