Segment information - Segment Adjusted EBITDA to Net Income (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Net income	$ 9,130,000	$ 7,798,000
Depreciation and amortization	3,811,000	3,938,000
Interest expense	2,809,000	2,466,000
Interest income	(67,000)	(81,000)
Provision for income taxes	2,148,000	1,885,000
EBITDA	17,831,000	16,006,000
(Gain) loss on sale or disposition of assets and sublease	(43,000)	(178,000)
Loss on early extinguishment of debt	94,000
Non-cash straight-line rent expense	231,000	147,000
Non-recurring severance and other related expenses	451,000
Acquisition integration and professional fees expense	183,000	18,000
Adjusted EBITDA	18,747,000	15,993,000
Operating Segments | Real Estate Franchise Services
Segment Reporting Information [Line Items]
Net income	8,972,000	8,370,000
Depreciation and amortization	3,732,000	3,868,000
Interest expense	2,793,000	2,462,000
Interest income	(67,000)	(81,000)
Provision for income taxes	2,120,000	1,983,000
EBITDA	17,550,000	16,602,000
(Gain) loss on sale or disposition of assets and sublease	(83,000)	(196,000)
Loss on early extinguishment of debt	94,000
Non-cash straight-line rent expense	274,000	212,000
Non-recurring severance and other related expenses	451,000
Acquisition integration and professional fees expense	183,000	18,000
Adjusted EBITDA	18,469,000	16,636,000
Operating Segments | Brokerages
Segment Reporting Information [Line Items]
Net income	158,000	(572,000)
Depreciation and amortization	79,000	70,000
Interest expense	16,000	4,000
Interest income	0	0
Provision for income taxes	28,000	(98,000)
EBITDA	281,000	(596,000)
(Gain) loss on sale or disposition of assets and sublease	(40,000)	(18,000)
Non-cash straight-line rent expense	(43,000)	(65,000)
Adjusted EBITDA	$ 278,000	$ (643,000)