Securities (Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	$ 1,472,565	$ 1,242,460
Available-for-sale Securities, Gross Unrealized Gains	43,738	32,569
Available-for-sale Securities, Gross Unrealized Losses	(10,228)	(7,030)
Available-for-sale Securities, Estimated Fair Value	1,506,075	1,267,999
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	1,451,313	1,219,071
Available-for-sale Securities, Gross Unrealized Gains	43,005	32,083
Available-for-sale Securities, Gross Unrealized Losses	(10,228)	(7,030)
Available-for-sale Securities, Estimated Fair Value	1,484,090	1,244,124
U.S. Government Corporations and Agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	21,002	104,719
Available-for-sale Securities, Gross Unrealized Gains	443	2,428
Available-for-sale Securities, Gross Unrealized Losses	(1)	0
Available-for-sale Securities, Estimated Fair Value	21,444	107,147
Mortgage-Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	1,027,234	815,408
Available-for-sale Securities, Gross Unrealized Gains	19,002	14,643
Available-for-sale Securities, Gross Unrealized Losses	(10,035)	(4,997)
Available-for-sale Securities, Estimated Fair Value	1,036,201	825,054
Obligations of States and Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	403,077	272,660
Available-for-sale Securities, Gross Unrealized Gains	23,560	14,983
Available-for-sale Securities, Gross Unrealized Losses	(192)	(973)
Available-for-sale Securities, Estimated Fair Value	426,445	286,670
Corporate Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	0	26,284
Available-for-sale Securities, Gross Unrealized Gains	0	29
Available-for-sale Securities, Gross Unrealized Losses	0	(1,060)
Available-for-sale Securities, Estimated Fair Value	0	25,253
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	21,252	23,389
Available-for-sale Securities, Gross Unrealized Gains	733	486
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Estimated Fair Value	$ 21,985	$ 23,875

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details