Income Taxes (Income Taxes - Additional Information) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
Deferred tax assets related to state net operating loss carryforwards	$ 9	$ 10
State net operating loss carryforwards specific valuation allowances	$ 25	22
State net operating loss carryforwards expiration date	Dec. 31, 2035
Deferred tax assets related to foreign tax credit carryforward	$ 3	5
Foreign tax credit carryforward expiration date	Dec. 31, 2025
Accrued interest liabilities, net of the related tax benefits	$ 1	1
Allocation of earnings for bad debt deductions of former thrift subsidiaries included in retained earnings	157	$ 157
Interest expense recognized in connection with income taxes	$ 1