Employee Benefit Plans (Amounts Recognized in the Financial Statements) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
BancShares Plan
Amounts recognized in the consolidated balance sheets
Other assets	$ 552	$ 0
Other liabilities	0	(36,949)
Net asset (liability) recognized	552	(36,949)
Amount recognized in accumulated other comprehensive income
Net loss (gain)	130,564	125,745
Less prior service cost	57	137
Accumulated other comprehensive loss, excluding income taxes	130,621	125,882
Actuarial loss	8,455
Prior service cost	57
Total	8,512
Bancorporation Plan
Amounts recognized in the consolidated balance sheets
Other assets	0	0
Other liabilities	(10,993)	(889)
Net asset (liability) recognized	(10,993)	(889)
Amount recognized in accumulated other comprehensive income
Net loss (gain)	32,409	19,117
Less prior service cost	0	0
Accumulated other comprehensive loss, excluding income taxes	32,409	$ 19,117
Actuarial loss	2,505
Prior service cost	0
Total	$ 2,505

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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