Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 20,888	$ 43,600	$ 63,985	$ 90,983
Other comprehensive income, net of tax:
Changes in unrealized gains/(losses) on available-for-sale securities	[1],[2]	(1,804)	2,704	5,873	5,567
Changes in unrealized gains on cash flow hedging instruments	[3],[4]	713	360	487	986
Foreign currency translation adjustment	[5]	5,293	1,732	1,315	2,068
Total other comprehensive income, net of tax		4,202	4,796	7,675	8,621
Comprehensive income		25,090	48,396	71,660	99,604
Changes in unrealized gains (losses) on available-for-sale securities, tax		(1,100)	1,700	4,800	3,500
Reclassifications to earnings of realized gains on available-for-sale securities		1,900	1,200	1,900	1,200
Reclassifications to earnings of losses on cash flow hedging instruments		1,000	1,600	2,200	3,300
Changes in unrealized gains on cash flow hedging instruments, tax		400	200	300	600
Foreign currency translation adjustment, tax		$ 3,300	$ 1,100	$ 800	$ 1,300

[1] Amounts are net of reclassifications to earnings of realized gains of $1.9 million and $1.2 million for the three months ended June 30, 2015 and 2014, respectively. Amounts are net of reclassifications to earnings of realized gains of $1.9 million and $1.2 million for the six months ended June 30, 2015 and 2014, respectively.

[2] Net of tax benefit of $1.1 million and taxes of $1.7 million for the three months ended June 30, 2015 and 2014, respectively. Net of taxes of $4.8 million and $3.5 million for the six months ended June 30, 2015 and 2014, respectively.

[3] Amounts are net of reclassifications to earnings of losses of $1.0 million and $1.6 million for the three months ended June 30, 2015 and 2014, respectively. Amounts are net of reclassifications to earnings of losses of $2.2 million and $3.3 million for the six months ended June 30, 2015 and 2014, respectively.

[4] Net of taxes of $0.4 million and $0.2 million for the three months ended June 30, 2015 and 2014, respectively. Net of taxes of $0.3 million and $0.6 million for the six months ended June 30, 2015 and 2014, respectively

[5] Net of taxes of $3.3 million and $1.1 million for the three months ended June 30, 2015 and 2014, respectively. Net of taxes of $0.8 million and $1.3 million for the six months ended June 30, 2015 and 2014, respectively