Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Abstract]
Deferred tax assets related to state net operating loss carryforwards	$ 10	$ 18
Operating loss carryforwards valuation allowances	$ 22	19
Operating loss carryforwards expiration date	Dec. 31, 2035
Deferred tax assets operating loss carryforwards foreign	$ 5
Foreign tax credit carryforward expiration date	Dec. 31, 2025
Accrued interest liabilities, net of the related tax benefits	$ 1	1
Retained earnings included allocation of earnings for bad debt deductions of former thrift subsidiaries	$ 157	$ 157