Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring Basis) (Detail) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 2,873,886	$ 3,106,931
Total financial assets held at fair value	2,923,630	3,155,928
Derivative instruments	24,820	24,038
Total financial liabilities held at fair value	24,820	24,038
Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	5,841	6,097
Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	477	565
Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	43,039	41,795
Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	387	540
U.S. Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	525	325
Agency CMOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	638,223	806,912
Agency MBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,090,820	1,226,702
Agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	80,383	70,977
CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	532,842	464,274
Collateralized loan obligations (CLOs) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	380,511	357,641
Pooled trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		28,490
Single issuer trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	39,382	34,935
Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	111,200	113,091
Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		3,584
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	525	3,634
Total financial assets held at fair value	6,374	9,763
Derivative instruments	450	259
Total financial liabilities held at fair value	450	259
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	5,841	6,097
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	8	32
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | U.S. Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	525	325
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Agency CMOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Agency MBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Collateralized loan obligations (CLOs) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Pooled trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Single issuer trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		3,309
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	2,873,361	3,074,807
Total financial assets held at fair value	2,916,779	3,117,110
Derivative instruments	24,370	23,779
Total financial liabilities held at fair value	24,370	23,779
Significant Other Observable Inputs (Level 2) [Member] | Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets
Significant Other Observable Inputs (Level 2) [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0	0
Significant Other Observable Inputs (Level 2) [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	43,031	41,763
Significant Other Observable Inputs (Level 2) [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	387	540
Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Other Observable Inputs (Level 2) [Member] | Agency CMOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	638,223	806,912
Significant Other Observable Inputs (Level 2) [Member] | Agency MBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,090,820	1,226,702
Significant Other Observable Inputs (Level 2) [Member] | Agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	80,383	70,977
Significant Other Observable Inputs (Level 2) [Member] | CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	532,842	464,274
Significant Other Observable Inputs (Level 2) [Member] | Collateralized loan obligations (CLOs) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	380,511	357,641
Significant Other Observable Inputs (Level 2) [Member] | Pooled trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Other Observable Inputs (Level 2) [Member] | Single issuer trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	39,382	34,935
Significant Other Observable Inputs (Level 2) [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	111,200	113,091
Significant Other Observable Inputs (Level 2) [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		275
Significant Unobservable Input (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		28,490
Total financial assets held at fair value	477	29,055
Derivative instruments
Total financial liabilities held at fair value
Significant Unobservable Input (Level 3) [Member] | Investments held In Rabbi Trust [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets
Significant Unobservable Input (Level 3) [Member] | Alternative investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	477	565
Significant Unobservable Input (Level 3) [Member] | Derivative instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Significant Unobservable Input (Level 3) [Member] | Mortgage banking derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Significant Unobservable Input (Level 3) [Member] | U.S. Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Unobservable Input (Level 3) [Member] | Agency CMOs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Unobservable Input (Level 3) [Member] | Agency MBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Unobservable Input (Level 3) [Member] | Agency CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Significant Unobservable Input (Level 3) [Member] | CMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Significant Unobservable Input (Level 3) [Member] | Collateralized loan obligations (CLOs) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Unobservable Input (Level 3) [Member] | Pooled trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		28,490
Significant Unobservable Input (Level 3) [Member] | Single issuer trust preferred securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Unobservable Input (Level 3) [Member] | Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities
Significant Unobservable Input (Level 3) [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities