Junior Subordinated Deferrable Interest Debentures Held By Trusts That Issued Guaranteed Capital Debt Securities (Narrative) (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Dec. 31, 2011
Debt [Line Items]
Ownership percentage	100.00%
Total of junior subordinated debentures held by the trusts	$ 244,793		$ 244,793
Private Bancorp Statutory Trust IV [Member]
Debt [Line Items]
Total of junior subordinated debentures held by the trusts	$ 143,760		$ 143,760
Earliest Redemption Date (on or after	Jun. 13, 2013	[1]
Replacement capital covenant terms committed	Under the replacement capital covenant, we committed, for the benefit of certain debt holders, that we would not repay, redeem or repurchase the Series IV Debentures or the related Trust Preferred Securities prior to June 2048 unless we have (1) obtained regulatory approval, and (2) raised certain amounts of qualifying equity or equity-like replacement capital within the 180 day period prior to the date of repayment, redemption or repurchase.

[1] The trust preferred securities are subject to mandatory redemption, in whole or in part, upon repayment of the Debentures at maturity or their earlier redemption. Subject to restrictions relating to our participation in the TARP CPP, the Debentures are redeemable in whole or in part prior to maturity at any time after the dates shown in the table, and in the case of Trust IV earlier at our discretion if certain events occur. It is anticipated that adoption of currently proposed capital rules would constitute a capital treatment event that would allow us to redeem early if certain conditions are satisfied, including those set forth in the replacement capital covenant to the extent then applicable. In addition, in any event, we may redeem only after we have obtained Federal Reserve approval, if then required under applicable guidelines or regulations.