Shareholders' Equity - Summary of Preferred and Common Share Activity (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity
Common stock, issued, beginning balance (in shares)	121,218,183
Treasury stock, beginning balance (in shares)	(10,525,147)
Grants of restricted stock (in shares)	171,974	177,493	169,870
Vesting of performance shares (in shares)	338,873	191,641	153,360
Issuance of common stock due to exercise of stock options (in shares)	1,810,559	897,622	1,661,808
Common stock, issued, ending balance (in shares)	117,218,183	121,218,183
Treasury stock, ending balance (in shares)	(9,497,940)	(10,525,147)
Performance Shares
Increase (Decrease) in Stockholders' Equity
Grants of restricted stock (in shares)	156,500	159,000	153,000
Common Stock
Increase (Decrease) in Stockholders' Equity
Common stock, issued, beginning balance (in shares)	121,218,183	124,218,183	127,218,183
Treasury stock, beginning balance (in shares)	(10,525,147)	(9,625,104)	(9,187,075)
Grants of restricted stock (in shares)	8,840	10,805	9,135
Forfeitures of restricted stock (in shares)		(7,500)
Issuance of common stock due to exercise of stock options (in shares)	1,810,559	897,622	1,661,808
Treasury stock acquired (in shares)	(5,103,591)	(4,950,868)	(5,228,868)
Retirement of treasury stock (in shares)	4,000,000	3,000,000	3,000,000
Common stock, issued, ending balance (in shares)	117,218,183	121,218,183	124,218,183
Treasury stock, ending balance (in shares)	(9,497,940)	(10,525,147)	(9,625,104)
Common Stock | Performance Shares
Increase (Decrease) in Stockholders' Equity
Vesting of performance shares (in shares)	311,399	149,898	119,896