Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring Basis) (Detail) - USD ($) $ in Thousands		Jun. 30, 2017	Dec. 31, 2016
Financial assets held at fair value:
Derivative Asset		$ 1,035	$ 0
Originated loans held for sale		39,407	60,260
Financial liabilities held at fair value:
Derivative liability		186	446
Alternative investments [Member]
Financial assets held at fair value:
Other assets		16,500
Fair Value, Measurements, Recurring [Member]
Financial assets held at fair value:
Total financial assets held at fair value		2,907,702	3,139,609
Financial liabilities held at fair value:
Derivative liability	[1]	21,445	45,189
Fair Value, Measurements, Recurring [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]	48,659	77,637
Fair Value, Measurements, Recurring [Member] | Available-for-sale Investment Securities [Member]
Financial assets held at fair value:
Available for sale investment securities		2,807,966	2,991,091
Fair Value, Measurements, Recurring [Member] | US Treasury Bill Securities [Member]
Financial assets held at fair value:
Available for sale investment securities		3,843	734
Fair Value, Measurements, Recurring [Member] | Agency CMO [Member]
Financial assets held at fair value:
Available for sale investment securities		359,016	419,706
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member]
Financial assets held at fair value:
Available for sale investment securities		875,690	954,349
Fair Value, Measurements, Recurring [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		587,102	573,272
Fair Value, Measurements, Recurring [Member] | CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		479,908	477,365
Fair Value, Measurements, Recurring [Member] | CLO [Member]
Financial assets held at fair value:
Available for sale investment securities		363,125	427,390
Fair Value, Measurements, Recurring [Member] | Single issuer trust preferred securities [Member]
Financial assets held at fair value:
Available for sale investment securities		31,202	28,633
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Financial assets held at fair value:
Available for sale investment securities		108,080	109,642
Fair Value, Measurements, Recurring [Member] | Investments held In Rabbi Trust [Member]
Financial assets held at fair value:
Other assets		5,083	5,119
Fair Value, Measurements, Recurring [Member] | Alternative investments [Member]
Financial assets held at fair value:
Other assets		6,587	5,502
Fair Value, Measurements, Recurring [Member] | Loan Origination Commitments [Member]
Financial assets held at fair value:
Originated loans held for sale		39,407	60,260
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Total financial assets held at fair value		9,035	6,103
Financial liabilities held at fair value:
Derivative liability	[1]	489	120
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]	109	250
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | Available-for-sale Investment Securities [Member]
Financial assets held at fair value:
Available for sale investment securities		3,843	734
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | US Treasury Bill Securities [Member]
Financial assets held at fair value:
Available for sale investment securities		3,843	734
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | Investments held In Rabbi Trust [Member]
Financial assets held at fair value:
Other assets		5,083	5,119
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | Alternative investments [Member]
Financial assets held at fair value:
Other assets		0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member] | Loan Origination Commitments [Member]
Financial assets held at fair value:
Originated loans held for sale		0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Total financial assets held at fair value		2,892,080	3,128,004
Financial liabilities held at fair value:
Derivative liability	[1]	20,956	45,069
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]	48,550	77,387
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale Investment Securities [Member]
Financial assets held at fair value:
Available for sale investment securities		2,804,123	2,990,357
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency CMO [Member]
Financial assets held at fair value:
Available for sale investment securities		359,016	419,706
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency MBS [Member]
Financial assets held at fair value:
Available for sale investment securities		875,690	954,349
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		587,102	573,272
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		479,908	477,365
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | CLO [Member]
Financial assets held at fair value:
Available for sale investment securities		363,125	427,390
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Single issuer trust preferred securities [Member]
Financial assets held at fair value:
Available for sale investment securities		31,202	28,633
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate debt securities [Member]
Financial assets held at fair value:
Available for sale investment securities		108,080	109,642
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Alternative investments [Member]
Financial assets held at fair value:
Other assets		0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Loan Origination Commitments [Member]
Financial assets held at fair value:
Originated loans held for sale		39,407	60,260
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Total financial assets held at fair value		6,587	5,502
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | CMBS [Member]
Financial assets held at fair value:
Available for sale investment securities		0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Alternative investments [Member]
Financial assets held at fair value:
Other assets		$ 6,587	$ 5,502

[1] or information relating to the impact of netting derivative assets and derivative liabilities as well as the impact from offsetting cash collateral paid to the same derivative counterparties see Note 12: Derivative Financial Instruments.