Employee Benefit Plans (Amounts Recognized in the Financial Statements) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Bancorporation Plan
Amounts recognized in the consolidated balance sheets
Other assets	$ 0	$ 0
Other liabilities	7,652	4,286
Net asset (liability) recognized	7,652	4,286
Amount recognized in accumulated other comprehensive income
Net loss (gain)	7,505	9,123
Less prior service cost	0	0
Accumulated other comprehensive loss, excluding income taxes	7,505	9,123
BancShares Plan
Amounts recognized in the consolidated balance sheets
Other assets	0	0
Other liabilities	(61,477)	(82,689)
Net asset (liability) recognized	(61,477)	(82,689)
Amount recognized in accumulated other comprehensive income
Net loss (gain)	70,358	80,806
Less prior service cost	556	767
Accumulated other comprehensive loss, excluding income taxes	70,914	$ 81,573
Actuarial loss	6,398
Prior service cost	210
Total	$ 6,608