Premises and Equipment Premises and Equipment (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Premises and Equipment [Line Items]
Premises and Equipment, Gross	$ 565,343,000	$ 530,622,000
Premises and Equipment, Accumulated Depreciation	299,423,000	267,887,000
Premises and Equipment, net	265,920,000	262,735,000
Depreciation Expense	33,000,000	32,000,000	33,000,000
Land [Member]
Premises and Equipment [Line Items]
Premises and Equipment, Gross	73,616,000	73,638,000
Building and Improvements [Member]
Premises and Equipment [Line Items]
Premises and Equipment, Gross	244,524,000	232,440,000
Software [Member]
Premises and Equipment [Line Items]
Premises and Equipment, Gross	89,183,000	82,801,000
Furniture and Equipment [Member]
Premises and Equipment [Line Items]
Premises and Equipment, Gross	$ 158,020,000	$ 141,743,000

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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