Supplemental Disclosure to Statements of Cash Flows - Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 21,039	$ 84,923	$ 24,211	$ 11,882
Restricted cash	17,392	10,899	14,865	13,803
Cash, cash equivalents and restricted cash	$ 38,431	$ 95,822	$ 39,076	$ 25,685

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