Supplemental Cash Flow Information - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
Cash and cash equivalents	$ 91,381	$ 55,306	$ 391,965
Restricted cash	30,548	$ 26,897	61,481
Cash, cash equivalents and restricted cash	$ 121,929		$ 453,446

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. 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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