Fair Value Measurements (Fair Value Assets And Liabilities Measured On Recurring and Nonrecurring Basis) (Detail) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Financial assets held at fair value:
Debt Securities, Available-for-sale		$ 2,960,103	$ 2,898,730
Derivative Asset		181,804	38,847
Loans Held-for-sale, Fair Value Disclosure		27,061	7,908
Financial liabilities held at fair value:
Derivative liability		1,314	36,515
US Treasury Bill Securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		19,924	7,550
Agency CMO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		200,956	234,923
Agency MBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		1,598,836	1,481,089
Agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		610,350	566,237
Non-agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		403,918	445,581
CLO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		94,805	112,771
Corporate debt securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		31,314	50,579
Fair Value, Recurring [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		2,960,103	2,898,730
Alternative Investment		3,217	2,563
Total financial assets held at fair value		3,196,397	2,959,786
Financial liabilities held at fair value:
Derivative liability	[1]	10,060	39,010
Fair Value, Recurring [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		19,924	7,550
Alternative Investment		0	0
Total financial assets held at fair value		25,255	12,615
Financial liabilities held at fair value:
Derivative liability	[1]	491	588
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		2,940,179	2,891,180
Alternative Investment		0	0
Total financial assets held at fair value		3,167,925	2,944,608
Financial liabilities held at fair value:
Derivative liability	[1]	9,569	38,422
Fair Value, Recurring [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Alternative Investment		3,217	2,563
Total financial assets held at fair value		3,217	2,563
Financial liabilities held at fair value:
Derivative liability			0
Fair Value, Recurring [Member] | Derivative instruments [Member]
Financial assets held at fair value:
Derivative Asset	[1]	201,343	46,278
Fair Value, Recurring [Member] | Derivative instruments [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Derivative Asset	[1]	658	758
Fair Value, Recurring [Member] | Derivative instruments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Derivative Asset	[1]	200,685	45,520
Fair Value, Recurring [Member] | Derivative instruments [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Derivative Asset			0
Fair Value, Recurring [Member] | Investments Held In Rabbi Trust [Member]
Financial assets held at fair value:
Other assets		4,673	4,307
Fair Value, Recurring [Member] | Investments Held In Rabbi Trust [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Other assets		4,673	4,307
Fair Value, Recurring [Member] | Investments Held In Rabbi Trust [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Other assets			0
Fair Value, Recurring [Member] | Loan Origination Commitments [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		27,061	7,908
Fair Value, Recurring [Member] | Loan Origination Commitments [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		0	0
Fair Value, Recurring [Member] | Loan Origination Commitments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		27,061	7,908
Fair Value, Recurring [Member] | Loan Origination Commitments [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Loans Held-for-sale, Fair Value Disclosure		0
Fair Value, Recurring [Member] | US Treasury Bill Securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		19,924	7,550
Fair Value, Recurring [Member] | US Treasury Bill Securities [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		19,924	7,550
Fair Value, Recurring [Member] | Agency CMO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		200,956	234,923
Fair Value, Recurring [Member] | Agency CMO [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		200,956	234,923
Fair Value, Recurring [Member] | Agency MBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		1,598,836	1,481,089
Fair Value, Recurring [Member] | Agency MBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		1,598,836	1,481,089
Fair Value, Recurring [Member] | Agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		610,350	566,237
Fair Value, Recurring [Member] | Agency CMBS [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	0
Fair Value, Recurring [Member] | Agency CMBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		610,350	566,237
Fair Value, Recurring [Member] | Agency CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	0
Fair Value, Recurring [Member] | Agency CMBS [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	0
Fair Value, Recurring [Member] | Non-agency CMBS [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		403,918	445,581
Fair Value, Recurring [Member] | Non-agency CMBS [Member] | Quoted Prices in Active Markets For Identical Assets (Level 1) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	0
Fair Value, Recurring [Member] | Non-agency CMBS [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		403,918	445,581
Fair Value, Recurring [Member] | Non-agency CMBS [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	0
Fair Value, Recurring [Member] | Non-agency CMBS [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		0	0
Fair Value, Recurring [Member] | CLO [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		94,805	112,771
Fair Value, Recurring [Member] | CLO [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		94,805	112,771
Fair Value, Recurring [Member] | Corporate debt securities [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		31,314	50,579
Fair Value, Recurring [Member] | Corporate debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets held at fair value:
Debt Securities, Available-for-sale		$ 31,314	$ 50,579

[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 13: Derivative Financial Instruments.