Subsequent Event Subsequent Event (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Subsequent Event
Subsequent Event, Date	Jan. 01, 2014
Subsequent Event, Description	Reclassify investment securities from available-for-sale to held-to-maturity
Investment securities, available-for-sale	$ 3,222,829,000	$ 3,683,005,000
Available-for-sale Securities, Gross Unrealized Gain Accumulated In Investments	49,801,000	101,778,000
State and local governments
Subsequent Event
Investment securities, available-for-sale	1,385,078,000	1,214,518,000
Available-for-sale Securities, Gross Unrealized Gain Accumulated In Investments	31,621,000	88,095,000
Reclassification of AFS to HTM
Subsequent Event
Percent Available-For-Sale Prior to Reclassification	100.00%
Percent Available-For-Sale Subsequent to Reclassification	85.00%
Percent Held-To-Maturity Subsequent to Reclassification	15.00%
Reclassification of AFS to HTM | State and local governments
Subsequent Event
Investment securities, available-for-sale	484,583,000
Available-for-sale Securities, Gross Unrealized Gain Accumulated In Investments	$ 4,624,000