Employee Benefit Plans - Additional Information (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012	Apr. 22, 2014
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		6.00%	6.00%	6.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		17,000,000	16,000,000			17,000,000
Document Period End Date		Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					574,257
Fair Value Per Unit of Restricted Stock Units					$ 21.67
Restricted Stock or Unit Expense		$ 2,000,000	$ 16,000,000	$ 27,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options		$ 65,000,000	54,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 2 months
Personal Pension Account Interest Crediting Rate		3.00%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year		7.00%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate		8 years
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate		5.00%
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation		$ 1,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation		1,000,000
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components		1,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components		1,000,000
Defined Benefit Plan, Effect of 25 Basis Point Change in Expected Long-Term Return on Plan Assets		7,000,000
Defined Benefit Plan, Effect of 25 Basis Point Change in the Discount Rate		1,000,000
Defined Contribution Plan, Cost Recognized		105,000,000	121,000,000	117,000,000
Performance Stock Units	[1]	$ 67,000,000	$ 32,000,000	$ 13,000,000
Performance Stock Units, Grants in Period		1,800,000	1,400,000	1,000,000
Performance Stock Unit, Unrecognized Compensation Expense		$ 87,000,000
Pension Plan [Member]
Defined Benefit Plan, Contributions by Employer	[2]	5,000,000	$ 5,000,000
Defined Benefit Plan, Future Amortization of Gain (Loss)		24,000,000
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Contributions by Employer	[3]	0	0
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)		6,000,000
Liability [Member]
Restricted Stock or Unit Expense			23,000,000
Long-term [Member]
Deferred Compensation Arrangement with Individual, Compensation Expense		291,000,000	245,000,000	$ 203,000,000
Short-term [Member]
Deferred Compensation Arrangement with Individual, Compensation Expense		$ 469,000,000	$ 448,000,000	$ 462,000,000

[1] Phantom stock units are settled in cash.

[2] Employer contributions represent the benefits that were paid to nonqualified plan participants. Unfunded nonqualified supplemental pension plans are not funded through plan assets.

[3] The Company contributed less than $1 million to the other postretirement benefits plans during both 2016 and 2015.