Earnings per Share - Reconciliation of Components Used to Derive Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income	$ 16,659	$ 2,350
Less: income allocated to unvested restricted stock	100	18
Income allocated to common shares	$ 16,559	$ 2,332
Weighted-average shares for basic EPS	30,461,681	30,469,022
Basic EPS	$ 0.54	$ 0.08
Effect of dilutive stock options and unvested performance restricted stock	12,289	3,877
Income allocated to common shares	$ 16,559	$ 2,332
Weighted-average shares for diluted EPS	30,473,970	30,472,899
Diluted EPS	$ 0.54	$ 0.08