Parent Company Only Financial Statements (Condensed Statements of Financial Condition) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 256,979	$ 189,460	$ 769,180	$ 1,628,137
Other assets	124,820us-gaap_OtherAssets	86,547us-gaap_OtherAssets
Total assets	4,819,646us-gaap_Assets	4,914,115us-gaap_Assets
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other liabilities	43,320us-gaap_OtherLiabilities	36,585us-gaap_OtherLiabilities
Total liabilities	4,025,071us-gaap_Liabilities	4,016,323us-gaap_Liabilities
Stockholders' equity	794,575us-gaap_StockholdersEquity	897,792us-gaap_StockholdersEquity	1,090,559us-gaap_StockholdersEquity	1,088,729us-gaap_StockholdersEquity
Total liabilities and shareholders’ equity	4,819,646	4,914,115
Parent [Member]
ASSETS
Cash and cash equivalents	123,144	252,848	100,642	113,602
Investment in subsidiaries	656,287	631,980
Other assets	19,121	3,024
Total assets	798,552	887,852
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other liabilities	3,977	(9,940)
Total liabilities	3,977	(9,940)
Stockholders' equity	794,575	897,792
Total liabilities and shareholders’ equity	$ 798,552	$ 887,852

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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