Earnings Per Share - Computation of Basic and Diluted Net Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income	$ 30,379	$ 52,278	$ 64,616	$ 27,482	$ 28,589	$ 63,015	$ 147,273	$ 119,086
Income allocable to common shares	30,379			27,482			147,273	119,086
Numerator for diluted earnings per share	$ 30,379			$ 27,482			$ 147,273	$ 119,086
Denominator:
Basic weighted average shares outstanding	57,935			57,603			57,843	57,609
Dilutive effect of unvested restricted stock	255			568			349	703
Diluted weighted average shares outstanding	58,190			58,171			58,192	58,312
Earnings per share:
Earnings per share, basic	$ 0.52			$ 0.48			$ 2.55	$ 2.07
Earnings per share, diluted	$ 0.52			$ 0.47			$ 2.53	$ 2.04