Business Combinations (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) company loan	Dec. 31, 2017 USD ($) loan	Sep. 30, 2018 USD ($) company
Business Combinations
Number of business banking franchises acquired | company	3		3
Combined business value after business combination			$ 3,100,000,000
Other acquisition and integration related costs	$ 5,598,000	$ 671,000
Severance and retention acquisition costs	3,569,000
Business combination one time pre-tax severance, retention, acquisition and integration costs	$ 9,167,000	$ 671,000
Number of loan classified as PCI loan | loan	0	0