Supplemental Cash Flow Information - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Cash, Cash Equivalents and Restricted Cash [Line Items]
Cash and cash equivalents	$ 80,044	$ 73,356	$ 78,687	$ 113,524	$ 120,357	$ 138,285
Total cash, cash equivalents, and restricted cash reported in the statements of cash flows	84,511	78,117	83,256	118,174	124,737	143,775
Prepaid Expenses and Other Current Assets
Cash, Cash Equivalents and Restricted Cash [Line Items]
Restricted cash and cash equivalents	3,441	3,733	3,286	3,275	2,926	5,106
Other Assets
Cash, Cash Equivalents and Restricted Cash [Line Items]
Restricted cash and cash equivalents	$ 1,026	$ 1,028	$ 1,283	$ 1,375	$ 1,454	$ 384

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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-Publisher FASB
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant