Fair Value Disclosures - Contingent Consideration Liability Change in Amount (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance		$ 6,541	$ 5,577	$ 6,541
Contingent Consideration from New Acquisition			0	1,525	$ 6,105
Payment of Contingent Consideration			2,552	2,631	310
Adjustment of Contingent Consideration			2,974	142
Ending Balance	$ 5,999		5,999	5,577	6,541
Sterner Insurance Associates Inc [Member]
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance		680	1,144	680
Contingent Consideration from New Acquisition		1,500	0	1,525
Payment of Contingent Consideration			1,325	1,751
Adjustment of Contingent Consideration			512	690
Ending Balance	331		331	1,144	680
Girard Partners [Member]
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance		5,503	4,241	5,503
Contingent Consideration from New Acquisition			0	0
Payment of Contingent Consideration			967	620
Adjustment of Contingent Consideration	5,300		2,394	(642)
Ending Balance	5,668		5,668	4,241	5,503
John T Fretz Insurance Agency [Member]
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance		$ 358	192	358
Contingent Consideration from New Acquisition			0	0
Payment of Contingent Consideration			260	260
Adjustment of Contingent Consideration			68	94
Ending Balance	$ 0		$ 0	$ 192	$ 358