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.

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Common Equity and Earnings Per Share - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Class of Stock
Payments of dividends, common stock
Preferred stock, shares issued
Preferred Stock, Shares Outstanding
Potential shares of common stock excluded from diluted earning per share calculation	27	2,037
Class A
Class of Stock
Common stock, votes per share		One
Class B
Class of Stock
Common stock, votes per share		Ten