Accumulated Other Comprehensive Income - Reclassifications (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities			$ 843		$ 487		$ 2,134
Interest expense - subordinated debentures and term loans	(731)		(1,187)		(2,189)		(4,460)
Other expenses - salaries and employee benefits	(20,616)		(20,083)		(61,943)		(59,078)
Income tax expense (benefit)	(2,667)		(3,926)		(11,490)		(12,714)
NET INCOME	10,403		11,236		33,083		34,812
Amount Reclassified from Accumulated Other Comprehensive Income for the Period
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
NET INCOME	(208)		339		(851)		447
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		[1]	843	[1]	487	[1]	2,134	[1]
Income tax expense (benefit)		[1]	(294)	[1]	(170)	[1]	(747)	[1]
NET INCOME		[1]	549	[1]	317	[1]	1,387	[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	(207)	[2]		[2]	(587)	[2]		[2]
Income tax expense (benefit)	72	[2]		[2]	205	[2]		[2]
NET INCOME	(135)	[2]		[2]	(382)	[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)		(323)		(1,209)		(1,446)
Income tax expense (benefit)	39		113		423		506
NET INCOME	$ (73)		$ (210)		$ (786)		$ (940)

[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.