Share-Based Compensation, Employee Incentive and Retirement Plans (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	May 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation		$ 53	$ 46	$ 41
Options outstanding, number		0
Unrecognized compensation expense related to non-vested share-based awards, other than options		$ 46
Total fair value of vested share-based awards, other than options		56	76	58
Contribution expense under 401(k) Plan		21	$ 19	$ 11
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to non-vested stock options		$ 0
Share-based Payment Arrangement, Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		2 years
Expiration period		7 years
Share-based Payment Arrangement, Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Expiration period		10 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards outstanding, number		100,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		1 year 7 months 6 days
Conversion of stock, shares issued		1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at December 31, 2018		1,987,000
Granted, shares		1,053,000
Vested(1)		(1,050,000)
Forfeited		(85,000)
Outstanding at December 31, 2019		1,905,000	1,987,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at December 31, 2017, weighted average		$ 39.87
Granted, weighted average		45.86
Released (vested), weighted average		34.53
Canceled/forfeited, weighted average		44.80
Outstanding at December 31, 2018, weighted average		$ 44.84	$ 39.87
Restricted Stock Units (RSUs) [Member] | Expected to vest [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at December 31, 2019		1,859,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at December 31, 2018, weighted average		$ 44.80
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		1 year
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Conversion of stock, shares issued		1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at December 31, 2018		229,000
Granted, shares		180,000
Vested(1)		(142,000)
Forfeited		0
Outstanding at December 31, 2019		267,000	229,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding at December 31, 2017, weighted average		$ 47.24
Granted, weighted average		46.70
Released (vested), weighted average		48.66
Canceled/forfeited, weighted average		0
Outstanding at December 31, 2018, weighted average		$ 46.12	$ 47.24
Performance Shares [Member] | Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
Performance Shares [Member] | Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
Performance Shares [Member] | Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
A2015Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant		6,900,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized under ESPP	4,000,000.0
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent		95.00%
Allocated share-based compensation expense		$ 0
Shares purchased under the plan		90,348
Employee Stock Purchase Plan | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85.00%