CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Net income	$ 93,742		$ 73,502		$ 147,213		$ 113,686
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on investments in available-for-sale securities	(3)	[1]	(16)	[1]	(6)	[1]	13	[1]
Unrealized gains (losses) on cash flow hedges	(1,533)	[2]	8,950	[2]	3,281	[2]	2,273	[2]
Total other comprehensive income (loss), net of tax	(1,536)		8,934		3,275		2,286
Comprehensive income	$ 92,206		$ 82,436		$ 150,488		$ 115,972

[1] Net of tax of ($2) and ($9) for the three months ended June 30, 2013 and 2012, respectively, and $(3) and $7 for the six months ended June 30, 2013 and 2012, respectively.

[2] Net of tax of ($825) and $4,819 for the three months ended June 30, 2013 and 2012, respectively, and $1,767 and $1,224 for the six months ended June 30, 2013 and 2012, respectively.