Income Taxes Income Taxes - NOL Usage Table (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Apr. 30, 2013	Dec. 31, 2010
Net Income Loss Reconciliation [Line Items]
TierABCCredit	$ 5,000
TierACreditUsage	2,297
NOL allocated amount	5,401,573
Ambac Assurance [Member]
Net Income Loss Reconciliation [Line Items]
AACNetTaxableIncome	43,743
Ambac [Member]
Net Income Loss Reconciliation [Line Items]
Bankruptcy Claims, Amount Paid to Settle Claims		1,900
Amount Of Loss Carry Forward Relinquish By Which Loss Carry Forward Exceed			3,400,000
Segregated Account [Member]
Net Income Loss Reconciliation [Line Items]
Bankruptcy Claims, Amount Paid to Settle Claims		100,000
Tier A [Member]
Net Income Loss Reconciliation [Line Items]
NOL allocated amount	479,000
NOL applicable percentage	15.00%
Tier B [Member]
Net Income Loss Reconciliation [Line Items]
NOL allocated amount	1,057,000
NOL applicable percentage	40.00%
Tier C [Member]
Net Income Loss Reconciliation [Line Items]
NOL allocated amount	1,057,000
NOL applicable percentage	10.00%
Tier D [Member]
Net Income Loss Reconciliation [Line Items]
NOL allocated amount	$ 1,057,000
NOL applicable percentage	15.00%