Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Effective Income Tax Rate Reconciliation [Line Items]
Tax benefit computed at federal statutory rate	$ 21,390	$ (37,615)	$ (24,711)
State income tax benefit, net of federal benefit	2,139	(3,762)	(2,471)
Permanent differences	1,771	93	319
Change in state tax rate on temporary differences	2,634
Liability for unrecognized tax benefits	(1,857)	(9,173)	(4,082)
Change in valuation allowance	(27,661)	41,375	25,114
Benefit for income taxes	$ (1,584)	$ (9,082)	$ (5,831)
Effective tax rate	2.60%	8.50%	8.30%

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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- Definition

The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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- Definition

The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to changes in the income tax rates under enacted tax laws in the period.

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- Definition

The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to total foreign income tax expense or benefit. The foreign income tax expense or benefit difference represents the income tax expense or benefit at applicable domestic statutory income tax rates applied to foreign earnings or loss for the period versus the foreign income tax expense or benefit calculated by applying the appropriate foreign tax rates.

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- Definition

The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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