Business Combinations - Estimated Fair Values of Aggregate Assets and Liabilities Acquired (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015
Other current assets	$ 1,992
Fixed assets	108
Goodwill	29,418
Purchased customer accounts	12,427
Non-compete agreements	58
Total assets acquired	44,003
Other current liabilities	(742)
Other liabilities	(1,408)
Total liabilities assumed	(2,150)
Net assets acquired	41,853
Liberty Insurance Brokers, Inc. and Affiliates (Liberty)
Other current assets	2,437
Fixed assets	40
Goodwill	8,689
Purchased customer accounts	4,289
Non-compete agreements	24
Total assets acquired	15,479
Other current liabilities	0
Other liabilities	(2,043)
Total liabilities assumed	(2,043)
Net assets acquired	13,436
Spain Agency, Inc.
Other current assets	0
Fixed assets	50
Goodwill	16,682
Purchased customer accounts	6,715
Non-compete agreements	21
Total assets acquired	23,468
Other current liabilities	(37)
Other liabilities	0
Total liabilities assumed	(37)
Net assets acquired	23,431
Other
Other current assets	(445)
Fixed assets	18
Goodwill	4,047
Purchased customer accounts	1,423
Non-compete agreements	13
Total assets acquired	5,056
Other current liabilities	(705)
Other liabilities	635
Total liabilities assumed	(70)
Net assets acquired	$ 4,986