Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Redeemable Convertible Preferred Stock Series B [Member]
Preferred stock, par or stated value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Preferred stock liquidation preference value (in dollars per share)	$ 1,000	$ 1,000	$ 1,000
Preferred stock shares authorized (in shares)	35,000	35,000
Preferred stock shares issued (in shares)	30,700	32,700	35,000
Preferred stock shares outstanding (in shares)	30,700	32,700	35,000
Redeemable Convertible Preferred Stock Series B [Member] \| Scenario, Previously Reported [Member]
Preferred stock shares authorized (in shares)		35,000	35,000
Common Class A [Member]
Common stock, par or stated value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock shares issued (in shares)	17,614,160	17,502,673	17,202,228
Common stock shares outstanding (in shares)	17,614,160	17,502,673	17,202,228

Face amount or stated value per share of common stock.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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