Final Purchase Price Allocation in Citadel Acquisition (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 16, 2011
Business Acquisition [Line Items]
Cash consideration to Citadel stockholders	$ 1,405,471
Common stock issued to Citadel stockholders	178,122	[1]
Stock-based compensation value	576
Cash consideration to Citadel to settle Citadel obligations	736,072
Total fair value for allocation	$ 2,320,241

[1] Fair value of the 22.7 million shares of the Company's common stock and warrants to purchase 47.6 million shares of the Company's common stock issued in the Citadel Merger and 2.4 million warrants held in reserve for potential future issuance related to the pending final settlement of certain outstanding unsecured claims arising from Citadel's emergence from bankruptcy, based on the closing price of the Company's Class A common stock on NASDAQ on September 15, 2011.