Investment Securities (Narrative) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Gross Unrealized Losses	$ (33,290)	$ (18,743)
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(25,412)	(14,292)
Securities available-for-sale, at fair value	2,984,631	2,793,873
Pledged Financial Instruments, Not Separately Reported, Securities	2,600,000	2,900,000
Agency collateralized mortgage obligations (agency CMO) [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(2,946)	(1,065)
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2,058)	(739)
Securities available-for-sale, at fair value	548,754	550,988
Agency mortgage-backed securities (agency MBS) [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(17,291)	(12,668)
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(19,908)	(11,340)
Securities available-for-sale, at fair value	1,065,109	1,028,518
Agency commercial mortgage-backed securities (agency CMBS) [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(959)	(134)
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(325)	(1,143)
Securities available-for-sale, at fair value	215,350	80,266
Non-agency commercial mortgage-backed securities (non-agency CMBS) [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(2,905)	(123)
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2,704)	(1,015)
Securities available-for-sale, at fair value	579,266	553,393
Collateralized loan obligations (CLO) [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(3,270)	(1,017)
Securities available-for-sale, at fair value	429,159	425,734
Single issuer trust preferred securities [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(4,998)	(3,736)
Securities available-for-sale, at fair value	37,170	38,245
Equity securities [Member]
Schedule of Investments [Line Items]
Gross Unrealized Losses	(921)	0
Securities available-for-sale, at fair value	2,578	5,903
Municipal bonds and notes [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(417)	$ (55)
Callable at the option of the counterparty [Member]
Schedule of Investments [Line Items]
Securities available-for-sale, at fair value	$ 961,600