Investment Securities (Summary Of Gross Unrealized Losses Not Considered OTTI) (Detail) $ in Thousands	Dec. 31, 2016 USD ($) holding	Dec. 31, 2015 USD ($) holding
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	$ 1,236,547	$ 1,295,959
Available for sale, Unrealized Losses - Less Than Twelve Months	(27,316)	(16,177)
Available for sale, Fair Value - Twelve Months or Longer	470,314	446,123
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (13,582)	$ (17,113)
Available for sale, Number of Holdings - Total | holding	168	156
Available for sale, Fair Value - Total	$ 1,706,861	$ 1,742,082
Available for sale, Unrealized Losses - Total	(40,898)	(33,290)
Held-to-maturity, Fair Value - Less Than Twelve Months	2,351,350	977,562
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(63,785)	(10,831)
Held-to-maturity, Fair Value - Twelve Months or Longer	292,225	542,714
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (9,315)	$ (14,581)
Held-to-maturity, Number of Holdings - Total | holding	395	152
Held-to-maturity, Fair Value - Total	$ 2,643,575	$ 1,520,276
Held-to-maturity, Unrealized Losses - Total	(73,100)	(25,412)
Agency collateralized mortgage obligations (agency CMO) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	107,853	195,369
Available for sale, Unrealized Losses - Less Than Twelve Months	(2,168)	(2,195)
Available for sale, Fair Value - Twelve Months or Longer	67,351	26,039
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (1,335)	$ (751)
Available for sale, Number of Holdings - Total | holding	15	14
Available for sale, Fair Value - Total	$ 175,204	$ 221,408
Available for sale, Unrealized Losses - Total	(3,503)	(2,946)
Held-to-maturity, Fair Value - Less Than Twelve Months	163,439	143,364
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(3,339)	(1,304)
Held-to-maturity, Fair Value - Twelve Months or Longer	17,254	27,928
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (485)	$ (754)
Held-to-maturity, Number of Holdings - Total | holding	16	13
Held-to-maturity, Fair Value - Total	$ 180,693	$ 171,292
Held-to-maturity, Unrealized Losses - Total	(3,824)	(2,058)
Agency mortgage-backed securities (agency MBS) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	512,075	481,839
Available for sale, Unrealized Losses - Less Than Twelve Months	(10,503)	(6,386)
Available for sale, Fair Value - Twelve Months or Longer	252,779	351,911
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (9,006)	$ (10,905)
Available for sale, Number of Holdings - Total | holding	97	84
Available for sale, Fair Value - Total	$ 764,854	$ 833,750
Available for sale, Unrealized Losses - Total	(19,509)	(17,291)
Held-to-maturity, Fair Value - Less Than Twelve Months	1,394,623	551,918
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(32,942)	(7,089)
Held-to-maturity, Fair Value - Twelve Months or Longer	273,779	470,828
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (8,826)	$ (12,819)
Held-to-maturity, Number of Holdings - Total | holding	150	87
Held-to-maturity, Fair Value - Total	$ 1,668,402	$ 1,022,746
Held-to-maturity, Unrealized Losses - Total	(41,768)	(19,908)
Agency commercial mortgage-backed securities (agency CMBS) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	554,246	124,241
Available for sale, Unrealized Losses - Less Than Twelve Months	$ (14,567)	$ (959)
Available for sale, Number of Holdings - Total | holding	32	7
Available for sale, Fair Value - Total	$ 554,246	$ 124,241
Available for sale, Unrealized Losses - Total	(14,567)	(959)
Held-to-maturity, Fair Value - Less Than Twelve Months	347,725	110,864
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	$ (1,348)	$ (325)
Held-to-maturity, Number of Holdings - Total | holding	25	7
Held-to-maturity, Fair Value - Total	$ 347,725	$ 110,864
Held-to-maturity, Unrealized Losses - Total	(1,348)	(325)
Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	12,427	276,330
Available for sale, Unrealized Losses - Less Than Twelve Months	(24)	(2,879)
Available for sale, Fair Value - Twelve Months or Longer	63,930	19,382
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (678)	$ (26)
Available for sale, Number of Holdings - Total | holding	12	29
Available for sale, Fair Value - Total	$ 76,357	$ 295,712
Available for sale, Unrealized Losses - Total	(702)	(2,905)
Held-to-maturity, Fair Value - Less Than Twelve Months	60,768	142,382
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	$ (411)	(1,983)
Held-to-maturity, Fair Value - Twelve Months or Longer		30,129
Held-to-maturity, Unrealized Losses, Twelve Months or Longer		$ (721)
Held-to-maturity, Number of Holdings - Total | holding	8	18
Held-to-maturity, Fair Value - Total	$ 60,768	$ 172,511
Held-to-maturity, Unrealized Losses - Total	(411)	(2,704)
Collateralized loan obligations (CLO) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	49,946	211,515
Available for sale, Unrealized Losses - Less Than Twelve Months	(54)	(2,709)
Available for sale, Fair Value - Twelve Months or Longer	50,237	15,708
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (465)	$ (561)
Available for sale, Number of Holdings - Total | holding	5	13
Available for sale, Fair Value - Total	$ 100,183	$ 227,223
Available for sale, Unrealized Losses - Total	(519)	(3,270)
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months		4,087
Available for sale, Unrealized Losses - Less Than Twelve Months		(128)
Available for sale, Fair Value - Twelve Months or Longer	28,633	33,083
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (1,748)	$ (4,870)
Available for sale, Number of Holdings - Total | holding	5	8
Available for sale, Fair Value - Total	$ 28,633	$ 37,170
Available for sale, Unrealized Losses - Total	(1,748)	(4,998)
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available for sale, Fair Value - Twelve Months or Longer	7,384
Available for sale, Unrealized Losses - Twelve Months or Longer	$ (350)
Available for sale, Number of Holdings - Total | holding	2
Available for sale, Fair Value - Total	$ 7,384
Available for sale, Unrealized Losses - Total	(350)	0
Equity Securities [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months		2,578
Available for sale, Unrealized Losses - Less Than Twelve Months		$ (921)
Available for sale, Number of Holdings - Total | holding		1
Available for sale, Fair Value - Total		$ 2,578
Available for sale, Unrealized Losses - Total		(921)
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity, Fair Value - Less Than Twelve Months	384,795	29,034
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(25,745)	(130)
Held-to-maturity, Fair Value - Twelve Months or Longer	1,192	13,829
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	$ (4)	$ (287)
Held-to-maturity, Number of Holdings - Total | holding	196	27
Held-to-maturity, Fair Value - Total	$ 385,987	$ 42,863
Held-to-maturity, Unrealized Losses - Total	$ (25,749)	$ (417)