Shareholders' Equity - Common Stock Rollforward (Details) - shares			6 Months Ended	12 Months Ended
	Feb. 26, 2020	Dec. 19, 2019	Jun. 30, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity
Common stock, shares issued, beginning balance (in shares)			140,726,677
Common shares, beginning balance (in shares)			132,325,790
Common stock acquired - share repurchase (in shares)	727,368	2,591,093	(8,100,000)	(21,100,000)
Share-based compensation programs (in shares)			1,900,000	2,300,000
Treasury Stock, Shares, Retired				0
Common stock, shares issued, ending balance (in shares)			143,048,960	140,726,677
Common shares, ending balance (in shares)			126,167,913	132,325,790
Common Stock
Increase (Decrease) in Stockholders' Equity
Common stock, shares issued, beginning balance (in shares)			140,700,000	272,400,000
Common shares, beginning balance (in shares)			132,300,000	151,000,000.0
Common shares issued (in shares)			0	100,000
Common stock acquired - share repurchase (in shares)			0	0
Share-based compensation programs (in shares)			2,300,000	3,200,000
Treasury Stock, Shares, Retired				(135,000,000.0)
Common stock, shares issued, ending balance (in shares)			143,000,000.0	140,700,000
Common shares, ending balance (in shares)			126,100,000	132,300,000
Treasury Stock
Increase (Decrease) in Stockholders' Equity
Common shares, held in treasury, beginning balance (in shares)			(8,400,000)	(121,400,000)
Common shares issued (in shares)			0	0
Common stock acquired - share repurchase (in shares)			(8,100,000)	(21,100,000)
Share-based compensation programs (in shares)			(400,000)	(900,000)
Treasury Stock, Shares, Retired				(135,000,000.0)
Common shares, held in treasury, ending balance (in shares)			(16,900,000)	(8,400,000)