Summarized Financial Information Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Total revenues	$ 302,830	$ 303,800	$ 290,916	$ 302,486	$ 244,097	$ 260,401	$ 246,816	$ 262,228	$ 1,200,032	$ 1,013,542	$ 973,492
Investment income									797	1,267	1,326
Amortization									63,573	54,755	51,442
Depreciation									15,373	12,392	12,639
Interest expense									16,097	14,132	14,471
Income before income taxes									304,811	270,521	266,098
Total assets	3,128,058				2,607,011				3,128,058	2,607,011	2,400,814
Capital expenditures									24,028	13,608	10,454
Retail
Segment Reporting Information [Line Items]
Total revenues									644,429	607,199	575,061
Investment income									108	102	170
Amortization									34,639	33,373	30,725
Depreciation									5,181	5,046	5,349
Interest expense									26,641	27,688	27,037
Income before income taxes									145,214	137,807	128,026
Total assets	2,420,759				2,155,413				2,420,759	2,155,413	1,914,587
Capital expenditures									5,732	6,102	4,852
National Programs
Segment Reporting Information [Line Items]
Total revenues									252,943	164,427	176,051
Investment income									20		1
Amortization									13,936	7,770	8,427
Depreciation									4,600	2,937	3,004
Interest expense									25,674	1,381	2,670
Income before income taxes									51,491	60,465	70,264
Total assets	1,183,191				680,251				1,183,191	680,251	624,540
Capital expenditures									9,633	1,968	2,377
Wholesale Brokerage
Segment Reporting Information [Line Items]
Total revenues									183,565	174,158	171,813
Investment income									22	34	29
Amortization									11,280	11,032	10,987
Depreciation									2,718	2,594	2,740
Interest expense									3,974	7,495	11,342
Income before income taxes									43,355	36,511	29,911
Total assets	837,364				712,212				837,364	712,212	673,927
Capital expenditures									3,383	2,658	1,893
Services
Segment Reporting Information [Line Items]
Total revenues									116,736	65,972	46,447
Investment income									1	128	15
Amortization									3,680	2,541	1,264
Depreciation									1,278	590	352
Interest expense									8,602	5,746	2,592
Income before income taxes									16,770	7,729	7,693
Total assets	238,430				166,060				238,430	166,060	145,321
Capital expenditures									2,519	689	419
Other
Segment Reporting Information [Line Items]
Total revenues									2,359	1,786	4,120
Investment income									646	1,003	1,111
Amortization									38	39	39
Depreciation									1,596	1,225	1,194
Interest expense									(48,794)	(28,178)	(29,170)
Income before income taxes									47,981	28,009	30,204
Total assets	(1,551,686)				(1,106,925)				(1,551,686)	(1,106,925)	(957,561)
Capital expenditures									$ 2,761	$ 2,191	$ 913