Investment Securities (Summary Of Gross Unrealized Losses Not Considered OTTI) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014 holding	Dec. 31, 2013 holding
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	$ 259,477	$ 893,274
Available for sale, Unrealized Losses - Less Than Twelve Months	(1,562)	(33,409)
Available for sale, Fair Value - Twelve Months or Longer	720,814	330,990
Available for sale, Unrealized Losses - Twelve Months or Longer	(17,181)	(28,217)
Available for sale, Number of Holdings - Total	94	123
Available for sale, Fair Value - Total	980,291	1,224,264
Available for sale, Unrealized Losses - Total	(18,743)	(61,626)
Held-to-maturity, Fair Value - Less Than Twelve Months	415,701	1,342,814
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(1,469)	(49,260)
Held-to-maturity, Fair Value - Twelve Months or Longer	702,497	187,778
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	(12,823)	(11,958)
Held-to-maturity, Number of Holdings - Total	89	164
Held-to-maturity, Fair Value - Total	1,118,198	1,530,592
Held-to-maturity, Unrealized Losses - Total	(14,292)	(61,218)
Agency CMO [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	47,217	149,894
Available for sale, Unrealized Losses - Less Than Twelve Months	(240)	(1,713)
Available for sale, Fair Value - Twelve Months or Longer	35,968	9,011
Available for sale, Unrealized Losses - Twelve Months or Longer	(825)	(155)
Available for sale, Number of Holdings - Total	8	15
Available for sale, Fair Value - Total	83,185	158,905
Available for sale, Unrealized Losses - Total	(1,065)	(1,868)
Held-to-maturity, Fair Value - Less Than Twelve Months	52,172	53,789
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(187)	(1,009)
Held-to-maturity, Fair Value - Twelve Months or Longer	24,942
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	(552)
Held-to-maturity, Number of Holdings - Total	6	4
Held-to-maturity, Fair Value - Total	77,114	53,789
Held-to-maturity, Unrealized Losses - Total	(739)	(1,009)
Agency MBS [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	3,691	616,286
Available for sale, Unrealized Losses - Less Than Twelve Months	(18)	(29,537)
Available for sale, Fair Value - Twelve Months or Longer	641,355	279,680
Available for sale, Unrealized Losses - Twelve Months or Longer	(12,650)	(18,161)
Available for sale, Number of Holdings - Total	64	88
Available for sale, Fair Value - Total	645,046	895,966
Available for sale, Unrealized Losses - Total	(12,668)	(47,698)
Held-to-maturity, Fair Value - Less Than Twelve Months	20,791	1,045,693
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(86)	(42,181)
Held-to-maturity, Fair Value - Twelve Months or Longer	608,568	170,780
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	(11,254)	(11,007)
Held-to-maturity, Number of Holdings - Total	44	94
Held-to-maturity, Fair Value - Total	629,359	1,216,473
Held-to-maturity, Unrealized Losses - Total	(11,340)	(53,188)
Agency CMBS [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	80,266	70,977
Available for sale, Unrealized Losses - Less Than Twelve Months	(134)	(782)
Available for sale, Number of Holdings - Total	4	3
Available for sale, Fair Value - Total	80,266	70,977
Available for sale, Unrealized Losses - Total	(134)	(782)
Held-to-maturity, Fair Value - Less Than Twelve Months	324,394	90,218
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(1,143)	(818)
Held-to-maturity, Number of Holdings - Total	17	4
Held-to-maturity, Fair Value - Total	324,394	90,218
Held-to-maturity, Unrealized Losses - Total	(1,143)	(818)
Non-agency CMBS [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	24,932	52,340
Available for sale, Unrealized Losses - Less Than Twelve Months	(117)	(996)
Available for sale, Fair Value - Twelve Months or Longer	9,396
Available for sale, Unrealized Losses - Twelve Months or Longer	(6)
Available for sale, Number of Holdings - Total	4	7
Available for sale, Fair Value - Total	34,328	52,340
Available for sale, Unrealized Losses - Total	(123)	(996)
Held-to-maturity, Fair Value - Less Than Twelve Months	13,003	106,527
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(30)	(4,059)
Held-to-maturity, Fair Value - Twelve Months or Longer	65,913	14,832
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	(985)	(916)
Held-to-maturity, Number of Holdings - Total	7	11
Held-to-maturity, Fair Value - Total	78,916	121,359
Held-to-maturity, Unrealized Losses - Total	(1,015)	(4,975)
Collateralized loan obligations (CLO) [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	99,221
Available for sale, Unrealized Losses - Less Than Twelve Months	(1,017)
Available for sale, Number of Holdings - Total	6
Available for sale, Fair Value - Total	99,221
Available for sale, Unrealized Losses - Total	(1,017)
Pooled trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months		0
Available for sale, Fair Value - Twelve Months or Longer		11,141
Available for sale, Unrealized Losses - Twelve Months or Longer		(3,410)
Available for sale, Number of Holdings - Total		2
Available for sale, Fair Value - Total		11,141
Available for sale, Unrealized Losses - Total		(3,410)
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Available for Sale, Fair Value - Less Than Twelve Months	4,150	3,777
Available for sale, Unrealized Losses - Less Than Twelve Months	(36)	(381)
Available for sale, Fair Value - Twelve Months or Longer	34,095	31,158
Available for sale, Unrealized Losses - Twelve Months or Longer	(3,700)	(6,491)
Available for sale, Number of Holdings - Total	8	8
Available for sale, Fair Value - Total	38,245	34,935
Available for sale, Unrealized Losses - Total	(3,736)	(6,872)
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity, Fair Value - Less Than Twelve Months	5,341	46,587
Held-to-maturity, Unrealized Losses - Less Than Twelve Months	(23)	(1,193)
Held-to-maturity, Fair Value - Twelve Months or Longer	3,074	2,166
Held-to-maturity, Unrealized Losses, Twelve Months or Longer	(32)	(35)
Held-to-maturity, Number of Holdings - Total	15	51
Held-to-maturity, Fair Value - Total	8,415	48,753
Held-to-maturity, Unrealized Losses - Total	$ (55)	$ (1,228)

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

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