Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of cash, cash equivalents, and restricted cash to balance sheet:
Cash and cash equivalents - unrestricted	$ 362,430	$ 103,437	$ 57,557
Cash and cash equivalents - restricted	57,966	45,652	21,153
Cash, cash equivalents, and restricted cash, end of period	$ 420,396	$ 149,089	$ 78,710	$ 81,190

Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant