Accumulated Other Comprehensive Income - Reclassifications (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities	$ 239		$ 502		$ 487		$ 1,291
Interest expense - subordinated debentures and term loans	(733)		(1,331)		(1,458)		(3,273)
Other expenses - salaries and employee benefits	(20,536)		(19,641)		(41,327)		(38,995)
Income tax expense (benefit)	(4,155)		(3,288)		(8,823)		(8,788)
NET INCOME	10,815		9,205		22,680		23,576
Amount Reclassified from Accumulated Other Comprehensive Income for the Period
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
NET INCOME	(43)		117		(643)		110
Amount Reclassified from Accumulated Other Comprehensive Income for the Period | Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities	239	[1]	502	[1]	487	[1]	1,291	[1]
Income tax expense (benefit)	(84)	[1]	(176)	[1]	(170)	[1]	(452)	[1]
NET INCOME	155	[1]	326	[1]	317	[1]	839	[1]
Amount Reclassified from Accumulated Other Comprehensive Income for the Period | Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Interest expense - subordinated debentures and term loans	(192)	[2]		[2]	(380)	[2]		[2]
Income tax expense (benefit)	67	[2]		[2]	133	[2]		[2]
NET INCOME	(125)	[2]		[2]	(247)	[2]		[2]
Amount Reclassified from Accumulated Other Comprehensive Income for the Period | Unrealized gains (losses) on defined benefit plans
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other expenses - salaries and employee benefits	(112)		(322)		(1,097)		(1,123)
Income tax expense (benefit)	39		113		384		394
NET INCOME	$ (73)		$ (209)		$ (713)		$ (729)

[1] For additional detail related to unrealized gains (losses) on available for sale securities and related amounts reclassified from accumulated other comprehensive income see NOTE 3. INVESTMENT SECURITIES.

[2] For additional detail related to unrealized gains (losses) on cash flow hedges and related amounts reclassified from accumulated other comprehensive income see NOTE 6. DERIVATIVE FINANCIAL INSTRUMENTS.