The aggregate expense charged against earnings to allocate the cost of acquired intangible assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.

No definition available.

Name:	us-gaap_AmortizationOfAcquiredIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Segment Reporting - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Community Banking \| Non Cash
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 1.4	$ 1.4	$ 1.4
Investment Management
Segment Reporting Information [Line Items]
Amortization of intangibles	$ 822.0