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Recent Accounting Guidance (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jan. 01, 2017
Recent Accounting Guidance
Restricted Cash and Cash Equivalents	$ 6,793	$ 6,862
Accounting Standards Update 2016-09
Recent Accounting Guidance
Excess tax benefits of deferred tax assets	2,800
Reduction in net cash provided by financing activities	$ 1,100	$ 2
Accounting Standards Update 2016-18 [Member]
Recent Accounting Guidance
Restricted Cash and Cash Equivalents			$ 6,900