Earnings Per Share - Summary of Earnings Per Share (Parenthetical) (Detail)	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Class A Stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Number of anti-dilutive warrants, options and restricted shares, for the year	55,309	1,057,573
CIBC World Markets Corp. [Member] \| January 2008 Acquisition [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Period for exercise of warrant	5 years
Acquisition date of CIBC World Markets Corp.	Jan. 14, 2008
Warrants expire date	2013-04-13
CIBC World Markets Corp. [Member] \| January 2008 Acquisition [Member] \| Class A Stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Company issued a warrant to purchase share of Class A Stock	1,000,000
Class A Stock exercisable	48.62

Class of warrant or right term exercise period.

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- Definition

Expiration date of warrants issued.

+ References

No definition available.

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- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

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- Definition

Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

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Exercise price per share or per unit of warrants or rights outstanding.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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