Segment Information - Schedule of Reconciliation of Net Income to EBITDA (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net income	$ 35,710	$ 31,555	$ 42,819	$ 37,110	$ 67,265	$ 79,930
Interest expense (income), net	1		(370)		57	(598)
Income tax expense	12,030		14,413		19,730	24,828
Depreciation and amortization					6,857	9,363
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	35,710		42,819		67,265	79,930
Interest expense (income), net	(1)		369		(57)	598
Income tax expense	12,030		14,413		19,730	24,828
Depreciation and amortization	3,399		4,566		6,793	9,299
EBITDA	51,138		62,167		93,731	114,655
Operating Segments [Member] | Residential [Member]
Segment Reporting Information [Line Items]
Net income	35,223		42,115		66,478	79,694
Interest expense (income), net	6		369		(50)	598
Income tax expense	11,866		14,178		19,466	24,750
Depreciation and amortization	3,258		3,277		6,525	6,731
EBITDA	50,353		59,939		92,419	111,773
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net income	487		704		787	236
Interest expense (income), net	(7)				(7)
Income tax expense	164		235		264	78
Depreciation and amortization	141		1,289		268	2,568
EBITDA	$ 785		$ 2,228		$ 1,312	$ 2,882