Estimated Fair Value Of Financial Instruments (Fair Value Measurements On A Recurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	$ 1,625,649		$ 1,783,465
Mortgage loans held for sale	35,342		32,049
Capital markets derivative assets	102,613	[1]	101,676	[1]
Other assets	305	[2]	759	[2]
Total assets	1,763,909		1,917,949
Capital markets derivative liabilities	105,773	[1]	104,140	[1]
Other liabilities	291	[2]	709	[2]
Total liabilities	106,064		104,849
US Treasury Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	88,252		61,521
US Government Agencies Debt Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale			10,034
Collateralized Mortgage Obligations [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	305,268		356,000
Residential Mortgage Backed Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	1,034,113		1,189,213
State And Municipal [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	197,516		166,197
Foreign Government Debt Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	500		500
Fair Value, Inputs, Level 1 [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	88,252		61,521
Total assets	88,252		61,521
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	88,252		61,521
Fair Value, Inputs, Level 2 [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	1,537,397		1,721,944
Mortgage loans held for sale	35,342		32,049
Capital markets derivative assets	101,486	[1]	100,849	[1]
Other assets	286	[2]	759	[2]
Total assets	1,674,511		1,855,601
Capital markets derivative liabilities	105,729	[1]	104,108	[1]
Other liabilities	291	[2]	709	[2]
Total liabilities	106,020		104,817
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale			10,034
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Obligations [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	305,268		356,000
Fair Value, Inputs, Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	1,034,113		1,189,213
Fair Value, Inputs, Level 2 [Member] | State And Municipal [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	197,516		166,197
Fair Value, Inputs, Level 2 [Member] | Foreign Government Debt Securities [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Total securities available-for-sale	500		500
Fair Value, Inputs, Level 3 [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Capital markets derivative assets	1,127	[1]	827	[1]
Other assets	19	[2]
Total assets	1,146		827
Capital markets derivative liabilities	44	[1]	32	[1]
Total liabilities	$ 44		$ 32

[1] Capital market derivative assets and derivative liabilities include client-related derivatives.

[2] Other assets and other liabilities include derivatives designated in hedging relationships, derivatives for commitments to fund certain mortgage loans held-for-sale, end-user foreign exchange derivatives and warrants received from one borrower in connection with a loan restructuring.