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BUSINESS COMBINATIONS - Schedule of Unaudited Pro forma Combined Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Combinations [Abstract]
Revenues									$ 783,177	$ 794,840	$ 774,210
Operating income									59,467	56,674	49,586
Net income									$ 91,064	$ 33,424	$ 11,708
Basic weighted average shares outstanding	50,436	48,370	48,348	48,005	47,811	47,690	47,464	45,913	48,793	47,226	42,688
Basic earnings per common share (in dollars per share)									$ 1.87	$ 0.71	$ 0.27
Diluted weighted average shares outstanding	50,719	48,619	48,563	48,262	48,583	48,361	48,221	45,913	49,045	47,966	44,168
Diluted earnings per common share (in dollars per share)									$ 1.86	$ 0.70	$ 0.27

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- Definition

The pro forma operating income for the period as if the business combination or combinations had been completed at the beginning of the period.

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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