Supplemental Information (Earnings Per Share) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share Reconciliation [Abstract]
Weighted-average Common Shares Outstanding – Basic	246,900,000	245,600,000	246,700,000	245,300,000
Assumed settlement of performance share units and restricted stock units	1,000,000.0	1,600,000	1,000,000.0	1,500,000
Dilutive effect of forward sale agreement	0	0	300,000	0
Weighted-average Common Shares Outstanding – Diluted	247,900,000	247,200,000	248,000,000.0	246,800,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	0	0	0	0