Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 201,029	$ 144,538
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	235	353
Net change in unrealized gains (losses) on available-for-sale securities	3,179	(2,041)
Other comprehensive income (loss)	3,414	(1,688)
Comprehensive income	$ 204,443	$ 142,850

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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