Segment Information - Schedule of Reconciliation of Net Income to EBITDA (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net income	$ 41,976	$ 35,710	$ 31,555	$ 29,471	$ 42,820	$ 37,110	$ 109,241	$ 109,401
Interest (income) expense, net	(744)			(222)			(801)	377
Income tax expense	13,790			9,829			33,520	34,657
Depreciation and amortization							10,477	13,164
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	41,976			29,471			109,241	109,401
Interest (income) expense, net	(744)			(222)			(801)
Income tax expense	13,790			9,829			33,520	34,657
Depreciation and amortization	3,587			3,769			10,380	13,067
EBITDA	58,609			42,847			152,340	157,502
Operating Segments [Member] | Residential [Member]
Segment Reporting Information [Line Items]
Net income	41,381			27,755			107,859	107,449
Interest (income) expense, net	(744)			(222)			(794)	377
Income tax expense	13,580			9,259			33,046	34,009
Depreciation and amortization	3,422			3,275			9,947	10,004
EBITDA	57,639			40,067			150,058	151,839
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net income	595			1,716			1,382	1,952
Interest (income) expense, net							(7)
Income tax expense	210			570			474	648
Depreciation and amortization	165			494			433	3,063
EBITDA	$ 970			$ 2,780			$ 2,282	$ 5,663