Fair Value Disclosures - Contingent Consideration Liability Change in Amount (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance	$ 339	$ 5,999
Contingent Consideration from New Acquisition	0	0
Payment of Contingent Consideration	131	5,413
Adjustment of Contingent Consideration	51	(247)
Ending Balance	259	339
Sterner Insurance Associates Inc [Member]
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance	0	331
Contingent Consideration from New Acquisition		0
Payment of Contingent Consideration		30
Adjustment of Contingent Consideration		(301)
Ending Balance		0
Girard Partners [Member]
Change in Contingent Consideration Liability [Roll Forward]
Beginning Balance	339	5,668
Contingent Consideration from New Acquisition	0	0
Payment of Contingent Consideration	131	5,383
Adjustment of Contingent Consideration	51	54
Ending Balance	$ 259	$ 339