Segment information - Reportable Segments Revenue and Adjusted EBITDA (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Continuing franchise fees									$ 72,706,000		$ 64,465,000		$ 56,350,000
Annual dues									30,726,000		29,524,000		28,909,000
Broker fees									28,685,000		24,811,000		19,579,000
Franchise sales and other franchise revenue									23,440,000		23,574,000		22,629,000
Brokerage revenue									15,427,000		16,488,000		16,210,000
Total revenue	42,565,000	44,240,000	42,299,000	41,880,000	40,234,000	40,312,000	39,241,000	39,075,000	170,984,000	[1],[2]	158,862,000	[1],[2]	143,677,000	[1],[2]
Total revenue	42,565,000	44,240,000	42,299,000	41,880,000	40,234,000	40,312,000	39,241,000	39,075,000	170,984,000	[1],[2]	158,862,000	[1],[2]	143,677,000	[1],[2]
Total segment reporting adjusted EBITDA									83,805,000		77,039,000		66,744,000
Operating Segments | Real Estate Franchise Services
Segment Reporting Information [Line Items]
Continuing franchise fees									74,199,000	[1]	65,728,000	[1]	57,599,000	[1]
Annual dues									30,729,000	[1]	29,527,000	[1]	28,913,000	[1]
Broker fees									29,014,000	[1]	25,078,000	[1]	19,797,000	[1]
Franchise sales and other franchise revenue									23,459,000	[1]	23,577,000	[1]	22,636,000	[1]
Total revenue									157,401,000	[1]	143,910,000	[1]	128,945,000	[1]
Total revenue									157,401,000	[1]	143,910,000	[1]	128,945,000	[1]
Total segment reporting adjusted EBITDA									83,227,000		75,490,000		65,191,000
Operating Segments | Brokerages
Segment Reporting Information [Line Items]
Continuing franchise fees									(1,493,000)	[1]	(1,263,000)	[1]	(1,249,000)	[1]
Annual dues									(3,000)	[1]	(3,000)	[1]	(4,000)	[1]
Broker fees									(329,000)	[1]	(267,000)	[1]	(218,000)	[1]
Franchise sales and other franchise revenue									(19,000)	[1]	(3,000)	[1]	(7,000)	[1]
Brokerage revenue									15,427,000	[1]	16,488,000	[1]	16,210,000	[1]
Total revenue									13,583,000	[1]	14,952,000	[1]	14,732,000	[1]
Total revenue									13,583,000	[1]	14,952,000	[1]	14,732,000	[1]
Total segment reporting adjusted EBITDA									$ 578,000		$ 1,549,000		$ 1,553,000

[1] Transactions between the Real Estate Franchise Services and the Brokerages reportable segments are eliminated in consolidation. Revenues for the Real Estate Franchise Services reportable segment include intercompany amounts paid from the Company’s Brokerage Services business of $1,844,000, $1,536,000 and $1,478,000 for the years ended December 31, 2014, 2013 and 2012, respectively. Such amounts are eliminated through the Brokerages reportable segment.

[2] Revenue recognized for fees assessed by the Company-owned brokerages for services provided to their affiliated real estate agents is entirely attributable to the Company’s U.S. operations. Revenue recognized for franchise services provided to the agents and franchisees in the Company’s network relates to operations in the U.S., Canada and outside of the U.S. and Canada.