CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	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	$ 56,225		$ 48,575		$ 203,438		$ 162,261
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on investments in available-for-sale securities	1,091	[1]	(14)	[1]	1,085	[1]	(1)	[1]
Unrealized gains (losses) on cash flow hedges	(3,327)	[2]	(3,126)	[2]	(46)	[2]	(853)	[2]
Total other comprehensive income (loss), net of tax	(2,236)		(3,140)		1,039		(854)
Comprehensive income	$ 53,989		$ 45,435		$ 204,477		$ 161,407

[1] Net of tax of $587 and ($8) for the three months ended September 30, 2013 and 2012, respectively, and $584 and ($1) for the nine months ended September 30, 2013 and 2012, respectively.

[2] Net of tax of ($1,791) and ($1,683) for the three months ended September 30, 2013 and 2012, respectively, and ($25) and ($459) for the nine months ended September 30, 2013 and 2012, respectively.