Securities (Details 5) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Investments in pooled trust preferred securities
Amortized Cost, Available for Sale	$ 475,814	$ 357,633
Securities available for sale	464,733	356,311
Gross Unrealized Losses, Available for Sale	(19,234)	(14,035)
Trust preferred securities [Member]
Investments in pooled trust preferred securities
Amortized Cost, Available for Sale	27,629	28,612
Securities available for sale	16,753	15,068
Gross Unrealized Losses, Available for Sale	(10,876)
XIII [Member]
Investments in pooled trust preferred securities
Amortized Cost, Available for Sale	1,155
Securities available for sale	1,140
Gross Unrealized Losses, Available for Sale	(15)
Issuers Currently in Deferral or Default (percent)	28.00%
XXIII [Member]
Investments in pooled trust preferred securities
Amortized Cost, Available for Sale	8,831
Securities available for sale	5,547
Gross Unrealized Losses, Available for Sale	(3,284)
Issuers Currently in Deferral or Default (percent)	21.00%
XXIV [Member]
Investments in pooled trust preferred securities
Amortized Cost, Available for Sale	12,076
Securities available for sale	6,782
Gross Unrealized Losses, Available for Sale	(5,294)
Issuers Currently in Deferral or Default (percent)	34.00%
XXVI [Member]
Investments in pooled trust preferred securities
Amortized Cost, Available for Sale	5,567
Securities available for sale	3,284
Gross Unrealized Losses, Available for Sale	$ (2,283)
Issuers Currently in Deferral or Default (percent)	31.00%