Accumulated Other Comprehensive Income (Loss) - Reclassifications (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities	$ 844	$ 239	$ 1,425	$ 487
Interest expense - subordinated debentures and term loans	(1,648)	(733)	(3,289)	(1,458)
Other expenses - salaries and employee benefits	(23,430)	(20,536)	(48,731)	(41,327)
Income tax expense	(5,642)	(4,155)	(10,011)	(8,823)
NET INCOME	15,160	10,815	28,780	22,680
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
NET INCOME	321	(43)	474	(643)
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) 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	844	239	1,425	487
Income tax expense	(295)	(84)	(499)	(170)
NET INCOME	549	155	926	317
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) 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	(351)	(192)	(695)	(380)
Income tax expense	123	67	243	133
NET INCOME	(228)	(125)	(452)	(247)
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) 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)		(1,097)
Income tax expense		39		384
NET INCOME	$ 0	$ (73)	$ 0	$ (713)