Segment Information - Schedule of Reconciliation of Net Income to EBITDA (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net income	$ 42,710	$ 47,218	$ 42,402	$ 41,976	$ 35,710	$ 31,555	$ 132,331	$ 109,241
Interest income, net	(208)			(744)			(801)	(801)
Income tax expense	14,435			13,790			43,938	33,520
Depreciation and Amortization							12,450	10,477
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	42,710			41,976			132,331	109,241
Interest income, net	(208)			(744)			(801)	(801)
Income tax expense	14,435			13,790			43,938	33,520
Depreciation and Amortization	4,535			3,587			12,450	10,380
EBITDA	61,472			58,609			187,918	152,340
Operating Segments [Member] | Residential [Member]
Segment Reporting Information [Line Items]
Net income	42,225			41,381			129,157	107,859
Interest income, net	(208)			(744)			(801)	(794)
Income tax expense	14,276			13,580			42,853	33,046
Depreciation and Amortization	4,326			3,422			11,855	9,947
EBITDA	60,619			57,639			183,064	150,058
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net income	485			595			3,174	1,382
Interest income, net								(7)
Income tax expense	159			210			1,085	474
Depreciation and Amortization	209			165			595	433
EBITDA	$ 853			$ 970			$ 4,854	$ 2,282