Income Taxes (Tables)

12 Months Ended

Dec. 31, 2011

Income Taxes [Abstract]

Components Of Provision For Income Taxes

	Year Ended December 31,
	2011			2010			2009
	(in thousands)
Current tax provision:
Federal	$	123,406		$	86,002		$	55,104
State		28,657			21,803			14,900
Foreign		(70	)		—			—
Total current		151,993			107,805			70,004
Deferred tax provision:
Federal		(14,008	)		(1,615	)		6,568
State		(4,589	)		653			(240	)
Total deferred		(18,597	)		(962	)		6,328
Provision for income taxes	$	133,396		$	106,843		$	76,332

Reconciliation Of Provision For Income Taxes

	Year Ended December 31,
	2011			2010			2009
	(in thousands)
Expected tax expense at U.S. federal statutory rate of 35%	$	125,833		$	93,694		$	67,267
State income taxes, net of Federal income tax effect		15,042			15,349			10,350
R&D tax credit		(8,365	)		(3,207	)		(1,616	)
Other		886			1,007			331
Provision for income taxes	$	133,396		$	106,843		$	76,332

Deferred Tax Assets And Liabilities

	As of December 31,
	2011			2010
	(in thousands)
Deferred tax assets/(liabilities):
Accruals and reserves	$	9,193		$	1,764
Depreciation		(17,381	)		(5,970	)
Stock-based compensation		39,337			19,084
R&D credits		6,335			4,351
Other		844			461
Deferred tax assets	$	38,328		$	19,690

Summary Of Changes In Unrecognized Tax Benefits

Balance as of December 31, 2009	$	13,244
Increases related to tax positions taken during prior periods		1,150
Increases related to tax positions taken during the current period		6,283
Balance as of December 31, 2010	$	20,677
Decreases related to tax positions taken during prior periods		(46	)
Increases related to tax positions taken during the current period		10,739
Decreases related to expiration of statute of limitations		(3,237	)
Balance as of December 31, 2011	$	28,133