Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2010
Operating Loss Carryforwards [Line Items]
Loss carry-forwards exceed		$ 3,400,000
Percentage of payment to IRS, Tier C	12.50%
Percentage of payment to IRS, Tier D	17.50%
Cash payment to settle tax years	2,000
Forfeiture amount over payment	1,234
Valuation Allowance	3,349,056
Expiration period	Expiring in 2028 and will fully expire in 2032
Operating tax carryforward expiration Year start	2028
Operating tax carryforward expiration Year End	2032
Federal Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating tax carry forward	7,435,696
Ambac Assurance [Member]
Operating Loss Carryforwards [Line Items]
Potential payment to outstanding disputes	100,000
Ambac [Member]
Operating Loss Carryforwards [Line Items]
Potential payment to outstanding disputes	$ 1,900