Pending Acquisitions - Expenditures Related to Pending Acquisition (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Professional services	$ 26,132	$ 22,341	$ 19,802
Travel/meals and entertainment	13,571	13,049	11,493
Other	152,077	139,469	137,593
Total non-interest expense	611,910	575,093	558,098
Acquisition-related Costs [Member]
Business Acquisition [Line Items]
Professional services	1,270
Travel/meals and entertainment	130
Other	34
Total non-interest expense	$ 1,434