Common Stock Outstanding and Earnings Per Share Data - Factors Used in Earnings Per Share Computations (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Basic
Net income available to common shareholders		$ 35,432	$ 44,643
Less: Earnings allocated to participating securities		(8)	(23)
Net income allocated to common shareholders		$ 35,424	$ 44,620
Weighted average common shares outstanding including participating securities		124,831,232	95,790,456
Less: Participating securities	[1]	(32,500)	(49,600)
Average shares	[2]	124,798,732	95,740,856
Basic earnings per common share		$ 0.28	$ 0.47
Diluted
Net income available to common shareholders		$ 35,424	$ 44,620
Weighted average common shares outstanding for basic earnings per common share	[2]	124,798,732	95,740,856
Add: Dilutive effects of stock based compensation awards		542,495	759,884
Average shares and dilutive potential common shares	[2]	125,341,227	96,500,740
Diluted earnings per common share		$ 0.28	$ 0.46

[1] Participating securities are restricted stock awards whereby the stock certificates have been issued, are included in outstanding shares, receive dividends and can be voted, but have not vested.

[2] Excludes participating shares