Earnings Per Share Reconciliation - Schedule of Earnings Per Common Share Reconciliation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings per common share:
Net earnings	$ 63,893	$ 37,980
Less: Net earnings allocated to restricted stock	309	83
Net earnings allocated to common shareholders	$ 63,584	$ 37,897
Weighted average shares outstanding	135,175	139,107
Basic earnings per common share	$ 0.47	$ 0.27
Diluted earnings per common share:
Net income allocated to common shareholders	$ 63,584	$ 37,897
Weighted average shares outstanding	135,175	139,107
Incremental shares from assumed exercise of outstanding options	253	209
Diluted weighted average shares outstanding	135,428	139,316
Diluted earnings per common share	$ 0.47	$ 0.27