Basis of Presentation and Summary of Significant Accounting Polices - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 30,115	$ 39,940	$ 39,940	$ 51,370
Current and long-term restricted cash	87,354	155,470		48,447
Total cash, cash equivalents, and restricted cash in the Consolidated Statements of Cash Flows	117,469	195,410		$ 99,817	$ 105,747
Average vault cash balance	$ 3,200,000	$ 3,100,000