Employee Benefit Plans (Amounts Recognized in the Financial Statements) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Bancorporation Plan
Amounts recognized in the consolidated balance sheets
Other assets	$ 0
Other liabilities	4,286
Net asset (liability) recognized	4,286
Amount recognized in accumulated other comprehensive income
Net loss (gain)	9,123
Less prior service cost	0
Accumulated other comprehensive loss, excluding income taxes	9,123
BancShares Plan
Amounts recognized in the consolidated balance sheets
Other assets	0	0
Other liabilities	(82,689)	(6,661)
Net asset (liability) recognized	(82,689)	(6,661)
Amount recognized in accumulated other comprehensive income
Net loss (gain)	80,806	16,605
Less prior service cost	767	977
Accumulated other comprehensive loss, excluding income taxes	81,573	17,582
Actuarial loss	11,335
Prior service cost	210
Total	$ 11,545

The pretax total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

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The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

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Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost.

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The aggregate net amount recognized in the balance sheet associated with the defined benefit plan(s). Will normally be the same as the Defined Benefit Plan, Funded Status of Plan, Total.

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Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

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This represents the entire assets recognized in the balance sheet that are associated with the defined benefit plans.

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Amount included in accumulated other comprehensive income (AOCI) related to gain (loss) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

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Amount included in accumulated other comprehensive income (AOCI) related to prior service cost (credit) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

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This represents the entire liability recognized in the balance sheet that is associated with the defined benefit plans.

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