Income Per Common Share - Narrative (Details) - USD ($)	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Sep. 17, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Amount authorized for repurchase				$ 2,000,000,000.0
Stock repurchased during period (in shares)		14,200,000
Stock repurchased and retired during period		$ 602,000,000	$ 122,000,000
Remaining authorized repurchase amount		$ 900,000,000
Dividends
Cash dividends per common share paid (in dollars per share)		$ 0.135	$ 0.120
Cash dividends per common share declared (in dollars per share)		$ 0.135	$ 0.120
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive effect on computation of diluted earnings per common share (in shares)		582,000	1,100,000
Performance Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive effect on computation of diluted earnings per common share (in shares)			20,000
Long-term stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive effect on computation of diluted earnings per common share (in shares)		7,000
Stock repurchased and retired during period to offset dilutive impact of awards granted (in shares)		400,000
Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock repurchased during period, value		$ 350,000,000
Stock repurchased during period, shares (in shares)		7,300,000
Stock repurchased during period, additional shares (in shares)		1,200,000
Subsequent Event [Member] | Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock repurchased during period, additional shares (in shares)	2,300,000