Subsequent Events (Details) (USD $) In Billions, unless otherwise specified	Apr. 25, 2012
Subsequent Event
Assets under management by acquired firm, Rochdale Investment Management	$ 4.8

Represents the amount that is asset under management of the Acquiree.

No definition available.

Name:	cyn_AssetUnderManagementOfAcquiree
Namespace Prefix:	cyn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant