Capital Stock (Tables)

12 Months Ended

Dec. 31, 2019

Federal Home Loan Banks [Abstract]

Summary Changes in Common Shares Outstanding

Common Shares Outstanding at December 31, 2016	119,515,894
Treasury stock purchases	(23,379,567	)
Exercise of stock options	243,775
Common Shares Outstanding at December 31, 2017	96,380,102
Issuance of restricted shares	589,736
Treasury stock purchases	(3,785,658	)
Issuance of shares to directors	13,249
Exercise of stock options	425,505
Common Shares Outstanding at December 31, 2018	93,622,934
Issuance of restricted stock and restricted stock units	564,729
Treasury stock purchases	(15,679	)
Vesting of restricted stock and restricted stock units	74,292
Exercise of stock options	215,300
Common Shares Outstanding at December 31, 2019	94,461,576