Quarterly Financial Data (Unaudited) - Acquisition and Integration Costs (Details) - USD ($)	3 Months Ended					12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Business Combinations
Pre-tax acquisition costs	$ 139,000	$ 199,000	$ 8,214,000	$ 615,000	$ 671,000		$ 671,000
Tax Cuts and Jobs Act of 2017 effect on re-measurement of net deferred tax assets					$ 7,103,000		7,103,000
Banking
Business Combinations
Pre-tax acquisition costs						$ 9,167,000
Tax Cuts and Jobs Act of 2017 effect on re-measurement of net deferred tax assets							$ 6,749,000