Premises and Equipment - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property Plant And Equipment [Abstract]
Operating lease, liability	$ 13,158,000
Operating lease, right-of-use asset	$ 12,500,000
Operating lease, weighted average remaining lease term	11 years 3 months 18 days
Operating lease, weighted average discount rate, percent	3.53%
Operating leases, rent expense		$ 394,000,000
Sale and leaseback transaction	$ 0	$ 0