Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 92,336	$ 176,067	$ 162,013
Other comprehensive income:
Changes in unrealized gains/(losses) on available-for-sale securities	[1],[2]	1,389	1,838	(48,528)
Changes in unrealized gains on cash flow hedging instruments, net of tax	[3]	1,088	2,141	6,917
Foreign currency translation adjustment, net of tax		(3,679)	(7,280)	1,663
Total other comprehensive income/(loss), net of tax		(1,202)	(3,301)	(39,948)
Comprehensive income		91,134	172,766	122,065
Changes in unrealized gains (losses) on available-for-sale securities, tax		700	2,100	24,900
Reclassifications to earnings of realized gains on available-for-sale securities		2,100	2,300	1,200
Reclassifications to earnings of losses on cash flow hedging instruments		$ 3,800	$ 6,100	$ 8,600

[1] Amounts are net of reclassifications to earnings of realized gains of $2.1 million, $2.3 million, and $1.2 million for the years ended December 31, 2015, 2014, and 2013, respectively

[2] Net of taxes of $0.7 million, $2.1 million, and $24.9 million for the years ended December 31, 2015, 2014, and 2013, respectively

[3] Amounts are net of reclassifications to earnings of losses of $3.8 million, $6.1 million, and $8.6 million for the years ended December 31, 2015, 2014, and 2013, respectively