Premises and Equipment (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Premises and Equipment
Cost	$ 522,054,000	$ 444,775,000
Accumulated Depreciation And Amortization	323,656,000	295,342,000
Carrying Value	198,398,000	149,433,000
Depreciation and amortization	32,267,000	32,485,000	27,596,000
Net rental payments on operating leases	56,400,000	52,500,000	45,400,000
Premises, including land
Premises and Equipment
Cost	206,313,000	158,389,000
Accumulated Depreciation And Amortization	114,330,000	105,933,000
Carrying Value	91,983,000	52,456,000
Land	15,011,000	3,511,000
Premises, including land | Maximum
Premises and Equipment
Range of Lives	39 years	39 years
Furniture, fixtures and equipment
Premises and Equipment
Cost	163,969,000	155,311,000
Accumulated Depreciation And Amortization	129,142,000	118,796,000
Carrying Value	34,827,000	36,515,000
Furniture, fixtures and equipment | Minimum
Premises and Equipment
Range of Lives	3 years	3 years
Furniture, fixtures and equipment | Maximum
Premises and Equipment
Range of Lives	10 years	10 years
Software
Premises and Equipment
Cost	151,772,000	131,075,000
Accumulated Depreciation And Amortization	80,184,000	70,613,000
Carrying Value	$ 71,588,000	$ 60,462,000
Range of Lives		5 years
Software | Minimum
Premises and Equipment
Range of Lives	5 years
Software | Maximum
Premises and Equipment
Range of Lives	10 years