Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 31, 2019	Jun. 30, 2019	Jun. 30, 2019
BancShares Plan
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions in current year		$ 0.0	$ 0.0
Defined Benefit Plan, Plan Assets, Contributions by Employer		0.0	0.0
Bancorporation Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 0.0	$ 0.0
Subsequent Event | BancShares Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 3.5