Acquisitions - Schedule of Final Purchase Price of Assets Acquired and Liabilities Assumed for Salin (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 26, 2019	Dec. 31, 2018
Loans
Goodwill	$ 145,690		$ 119,880
Salin Bancshares, Inc [Member]
Assets
Cash and due from banks		$ 152,745
Investment securities, available for sale		54,706
Loans
Total loans		571,819
Premises and equipment, net		23,882
FRB and FHLB stock		3,571
Goodwill		25,810
Core deposit intangible		21,111
Interest receivable		2,488
Other assets		107,611
Total assets purchased		963,743
Common shares issued		102,722
Cash paid		24,000
Total purchase price		126,722
Deposits
Non-interest bearing		188,744
NOW accounts		207,567
Savings and money market		274,504
Certificates of deposit		70,652
Total deposits		741,467
Borrowings		70,495
Subordinated debentures		17,443
Interest payable		826
Other liabilities		6,790
Total liabilities assumed		837,021
Salin Bancshares, Inc [Member] | Residential Mortgage [Member]
Loans
Total loans		136,089
Salin Bancshares, Inc [Member] | Commercial [Member]
Loans
Total loans		350,916
Salin Bancshares, Inc [Member] | Consumer [Member]
Loans
Total loans		$ 84,814