Acquisitions (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary of merger-related expenses
Salaries and employee benefits	$ 1,203,993	$ 999,709	$ 1,001,873
Equipment and net occupancy	249,514	216,064	211,391
Printing, postage and supplies	40,917	33,847	38,216
Other costs of operations	821,797	527,790	568,309
Total merger-related expenses	84,000
K Bank and Wilmington Trust Corporation Acquisition [Member]
Summary of merger-related expenses
Salaries and employee benefits	16,131	7	10,030
Equipment and net occupancy	412	44	2,975
Printing, postage and supplies	2,663	74	3,677
Other costs of operations	64,481	646	72,475
Total merger-related expenses	$ 83,687	$ 771	$ 89,157