Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 2,215	$ 157,208	$ 5,248	$ 163,321
Other comprehensive income (loss), net of tax:
Change in foreign currency translation	40	4	(220)	65
Change in fair value of available for sale securities	103		(1,139)
Change in fair value of interest rate swap agreements		451		1,287
Total other comprehensive income (loss)	143	455	(1,359)	1,352
Comprehensive income (loss)	$ 2,358	$ 157,663	$ 3,889	$ 164,673

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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