Common Share and Earnings Per Common Share (Narrative) (Details) - USD ($)	6 Months Ended
	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Jul. 01, 2019	Jan. 31, 2019
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount			$ 100,000,000	$ 250,000,000.0		$ 500,000,000.0
Number of shares authorized to be repurchased (in shares)					9,250,000
Stock repurchased during period (in shares)	24,784,910
Stock repurchased during period	$ 491,900,000
Average repurchase price per share (in dollars per share)	$ 19.85
Remaining authorized repurchase amount	$ 73,300,000
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount		$ 250,000,000.0