Changes in Carrying Amount of Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended		12 Months Ended
Dec. 31, 2012	Mar. 31, 2013	Dec. 31, 2012 Bank [Member]	Mar. 31, 2013 Bank [Member]	Mar. 31, 2013 Institutional Investment Management [Member]	Dec. 31, 2012 Institutional Investment Management [Member]	Dec. 31, 2011 Institutional Investment Management [Member]	Mar. 31, 2013 Asset Servicing [Member]	Dec. 31, 2012 Asset Servicing [Member]	Dec. 31, 2011 Asset Servicing [Member]
Goodwill And Other Intangible Assets [Line Items]
Beginning Balance	$ 211,114	$ 209,758	$ 144,109	$ 142,753	$ 47,529	$ 47,529	$ 47,529	$ 19,476	$ 19,476	$ 19,476
Goodwill disposals during period	(1,356)		(1,356)
Ending Balance	$ 209,758	$ 209,758	$ 142,753	$ 142,753	$ 47,529	$ 47,529	$ 47,529	$ 19,476	$ 19,476	$ 19,476

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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