Summary of Significant Accounting Policies - Cumulative Effect of the Changes Made to the Company's Balance Sheet upon Adopting ASC 606 (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets:
Other current assets	$ 3,817	$ 3,272	$ 2,332
Other assets	45,785	14,673	17,050
Deferred income taxes	114,372	28,497	28,550
Liabilities:
Deferred revenue, current portion		12,322	10,800
Deferred revenue	27,852	18,084	22,260
Equity:
Retained earnings	2,420	2,917	2,693
Noncontrolling interest	$ 420,194	566,082	$ 565,142
ASU 2014-09
Assets:
Other current assets		940
Other assets		(2,377)
Deferred income taxes		(53)
Liabilities:
Deferred revenue, current portion		1,522
Deferred revenue		(4,176)
Equity:
Retained earnings		224
Noncontrolling interest		$ 940