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		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Class of Stock
Payments of dividends, common stock			$ 0		$ 0
Preferred stock, shares issued	0		0		0
Preferred stock, shares outstanding	0		0		0
2013 Plan
Class of Stock
Shares issuable under stock options excluded from calculation of diluted earnings per share	318,000	1,260,000	276,000	970,000
Class A
Class of Stock
Common stock, votes per share			One
Class B Convertible
Class of Stock
Common stock, votes per share			Ten