Provision (Benefit) for Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Provision For Income Taxes [Line Items]
Income Taxes Receivable	$ 19	$ 38
Proceeds from Income Tax Refunds	38		$ 39
Income Taxes Paid		2
Deferred Other Tax Expense (Benefit)	(10)	(5)	$ (12)
Federal Excess Business Interest Expense Carryover	20
Deferred Tax Assets, Capital Loss Carryforwards	$ 48
Operating Loss Carryforwards, Limitations on Use	50 percent
AMT Credit Carryforward Refund	$ 50
Income Tax Examination, Penalties and Interest Accrued	1
Unrecognized Tax Benefits	9
Deferred Tax Assets, Tax Credit Carryforwards, Other	$ 7
Uncertain tax position expiration period	12 months
Domestic Tax Authority [Member]
Provision For Income Taxes [Line Items]
Operating Loss Carryforwards	$ 2,100
State and Local Jurisdiction [Member]
Provision For Income Taxes [Line Items]
Operating Loss Carryforwards	$ 4,200	$ 4,100
Percentage Deferred Tax Assets Operating Loss Carryforwards State That Expire	99.00%
RKI [Member] | Domestic Tax Authority [Member]
Provision For Income Taxes [Line Items]
Operating Loss Carryforwards	$ 218
Maximum
Provision For Income Taxes [Line Items]
Operating Loss Carryforwards, Limitations on Use	three