Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Securities held to maturity, fair values	$ 119,481	$ 152,566
Mortgage loans held for sale recorded at fair value	$ 139,950	$ 97,273
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	5,000,000us-gaap_PreferredStockSharesAuthorized	5,000,000us-gaap_PreferredStockSharesAuthorized
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	50,000,000us-gaap_CommonStockSharesAuthorized	50,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	35,262,901us-gaap_CommonStockSharesIssued	31,917,385us-gaap_CommonStockSharesIssued
Treasury stock, shares	1,809,497us-gaap_TreasuryStockShares	2,130,841us-gaap_TreasuryStockShares

Face amount or stated value per share of common stock.

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Fair value of investments in debt securities classified as held-to-maturity.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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