Segment Information - Schedule of Reconciliation of Net Income to EBITDA (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net income (loss)	$ 18,299	$ 20,098	$ 28,782	$ 27,949	$ 12,629	$ 7,787	$ 23,725	$ 23,706	$ 95,128	$ 67,847	$ 48,098
Interest									461	1,125	619
Taxes									46,791	34,983	28,689
Depreciation and amortization									16,860	$ 14,498	$ 14,384
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income (loss)									95,128
Interest									461
Taxes									46,791
Depreciation and amortization									16,730
EBITDA									159,110
Operating Segments [Member] | Residential [Member]
Segment Reporting Information [Line Items]
Net income (loss)									97,412
Interest									461
Taxes									47,911
Depreciation and amortization									14,598
EBITDA									160,382
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net income (loss)									(2,284)
Taxes									(1,120)
Depreciation and amortization									2,132
EBITDA									$ (1,272)