Goodwill and Other Intangible Assets - Summary of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 112,657	$ 67,717
Goodwill, Acquired During Period	59,902	44,940
Goodwill, Ending Balance	172,559	112,657
Banking [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	78,574	35,058
Goodwill, Acquired During Period	59,902	43,516
Goodwill, Ending Balance	138,476	78,574
Wealth Management [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	15,434	15,434
Goodwill, Acquired During Period	0	0
Goodwill, Ending Balance	15,434	15,434
Insurance [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	18,649	17,225
Goodwill, Acquired During Period	0	1,424
Goodwill, Ending Balance	$ 18,649	$ 18,649