Income Taxes Income Taxes - NOL Usage Table (Details) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended	12 Months Ended	18 Months Ended
	Jun. 30, 2016	Sep. 30, 2011	Dec. 31, 2015	Jun. 30, 2016
Net Income Loss Reconciliation [Line Items]
Income Tax Examination, Penalties and Interest Accrued	$ 3,650,000			$ 3,650,000
Tolling Payment Payable to AFG	1,120		$ 70,911	1,120
TierABCCredit	10,000
TierACreditUsage	5,000
NOL allocated amount	4,245,743			4,245,743
Ambac Assurance [Member]
Net Income Loss Reconciliation [Line Items]
Percentage Of Notional Federal Tax Liability		25.00%
AACNetTaxableIncome			877,313	885,312
NOL allocated amount	2,764,688			2,764,688
AACNetTaxableIncomeFromTierA			479,000
AACNetTaxableIncomeFromTierB	7,998		398,313
AFG [Member]
Net Income Loss Reconciliation [Line Items]
Percentage Of Notional Federal Tax Liability		50.00%
NOL allocated amount	$ 1,387,903			$ 1,387,903
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%