Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax Credit Carryforward [Line Items]
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		$ 0	$ 0	$ 0
Income Tax Examination, Penalties and Interest Accrued	$ 3,650,000
NOL allocated amount		4,027,329
AFG [Member]
Tax Credit Carryforward [Line Items]
NOL allocated amount		1,389,359
Percentage Of Notional Federal Tax Liability	50.00%
U. S. Federal Net Operating Tax [Member]
Tax Credit Carryforward [Line Items]
NOL allocated amount		3,953,235
United States [Member]
Tax Credit Carryforward [Line Items]
NOL allocated amount		$ 74,094
Minimum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2029
Maximum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date		Dec. 31, 2033