Consolidated Statements Of Comprehensive Income (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 69,690,000		$ 37,710,000		$ 113,745,000		$ 98,619,000
Unrealized gains on available-for-sale securities, net of tax	(8,160,000)	[1]	8,356,000	[1]	(48,158,000)	[1]	12,714,000	[1]
Unrealized gains on cash flow hedging instruments, net of tax	473,000	[2]	463,000	[2]	5,420,000	[2]	1,492,000	[2]
Foreign currency translation adjustment, net of tax	2,669,000		1,049,000		1,393,000		1,439,000
Total other comprehensive income	(5,018,000)		9,868,000		(41,345,000)		15,645,000
Comprehensive income	64,672,000		47,578,000		72,400,000		114,264,000
Reclassifications to earnings of realized gains on available-for-sale securities	200,000		400,000		1,100,000		1,600,000
Reclassifications to earnings of losses on cash flow hedging instruments	$ 2,100,000		$ 2,800,000		$ 6,700,000		$ 9,000,000

[1] Net of taxes of $5.4 million and $5.2 million for the three months ended September 30, 2013 and 2012, respectively, and $29.6 million and $7.9 million for the nine months ended September 30, 2013 and 2012, respectively.Amounts are net of reclassifications to earnings of realized gains of $0.2 million and $0.4 million for the three months ended September 30, 2013 and 2012, respectively. Amounts are net of reclassifications to earnings of realized gains of $1.1 million and $1.6 million for the nine months ended September 30, 2013 and 2012, respectively.

[2] Amounts are net of reclassifications to earnings of losses of $2.1 million and $2.8 million for the three months ended September 30, 2013 and 2012, respectively. Amounts are net of reclassifications to earnings of losses of $6.7 million and $9.0 million for the nine months ended September 30, 2013 and 2012, respectively.