Summary of Significant Accounting Policies - Debt Issuance and Amendment Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Debt issuance costs related to amendment	$ 2,309	$ 1,976	$ 1,507
Capitalized debt issuance costs	17,200	14,900
Accumulated amortization of debt issuance costs	10,500	8,600
Amortization expense related to capitalized debt issuance costs	$ 1,870	$ 1,270	$ 1,321