Share-based Compensation (Narrative) (Details)		1 Months Ended						3 Months Ended			7 Months Ended	9 Months Ended	12 Months Ended
	Jul. 13, 2016 USD ($) shares	Oct. 31, 2017 shares	Sep. 30, 2017 shares	Mar. 31, 2017 $ / shares shares	Dec. 31, 2015 USD ($)	May 31, 2014	Jul. 31, 2011	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jul. 31, 2016 USD ($) shares	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($) item $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Aug. 01, 2016 $ / shares	Jul. 26, 2016 shares	Jan. 31, 2015 $ / shares	Apr. 16, 2013 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, options granted													2,853,000	4,858,460
Weighted average exercise price of options granted during the period (per share) | $ / shares													$ 3.69	$ 7.12
Options Outstanding, Units, Exercised														1,109	772
Options Outstanding, Value, Exercised | $															$ 4,800
Weighted average grant date fair value of options granted during the period (per share) | $ / shares													2.44	$ 7.12	$ 20.67
Equity instruments number of shares authorized as a percentage of equity value						10.00%
Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of options granted during the period (per share) | $ / shares													$ 2.44	$ 7.12	$ 20.67
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense | $													$ 2,500,000
Weighted average period for recognition of compensation expense													2 years 10 months 24 days
Share based compensation, options granted													1,040,000
Weighted average exercise price of options granted during the period (per share) | $ / shares													$ 2.42
Options Outstanding, Units, Exercised													0
Number of executives | item													3
Expected dividend yield													0.00%
Expected life													6 years
Risk-free interest rate													2.22%
Volatility													74.92%
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, options granted														1,630,536
Employees and Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, options granted														3,227,924
Option Agreement, December 31, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense | $									$ 5,100,000				$ 2,900,000	$ 7,200,000
Option Agreement, December 31, 2015 [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, options granted															769,231
Share based compensation, options granted, value | $					$ 15,200,000
Option Agreement, December 31, 2015 [Member] | Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage													33.30%
Option Agreement, December 31, 2015 [Member] | Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage													33.30%
Option Agreement, December 31, 2015 [Member] | Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage													33.30%
Option Agreement, July 13, 2016 [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, options granted	1,630,536
Modification charge | $	$ 12,400,000
Incremental modification charge | $												$ 8,300,000
Company's outstanding common equity at IPO date, percentage	5.00%
Percentage of options forfeited	25.00%
Additional year of service	2 years
Option Agreement, July 13, 2016 [Member] | Tranche One [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental modification charge | $	$ 4,100,000
2011 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance																	0
2016 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional units available for grant														8,496,872
Increase in authorized shares as a percentage of common stock issued													4.00%
Incentive plan termination period													10 years
Shares authorized for issuance											6,720,000		8,523,147
Unrecognized compensation expense | $													$ 13,300,000	$ 21,700,000
Weighted average period for recognition of compensation expense													1 year 10 months 24 days	1 year 8 months 12 days
Stock compensation expense | $													$ 12,400,000	$ 24,600,000	$ 10,300,000
2016 Equity Incentive Plan [Member] | January 2015 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental modification charge | $										$ 1,100,000
Stock compensation expense | $										$ 668,000
2016 Equity Incentive Plan [Member] | July 2016 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental modification charge | $	4,000,000
Stock compensation expense | $								$ 1,800,000
Remaining stock compensation | $	$ 2,200,000
Number of shares affected by modification	1,600,000
2016 Equity Incentive Plan [Member] | Tranche One [Member] | January 2015 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period													1 year
2016 Equity Incentive Plan [Member] | Tranche Two [Member] | January 2015 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period													2 years
2014 Long-Term Incentive Plan (“LTIP”) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense | $								$ 22,600,000			$ 0
Equity instruments granted													9,750	9,750
Equity instrument payable, common stock value percent above grant price													333.00%
Equity instrument payable, common stock value | $ / shares													$ 20.00
2014 Long-Term Incentive Plan (“LTIP”) [Member] | Equity Appreciation Rights Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments granted														1,250	8,500
Equity instruments base price | $ / shares														$ 6.00	$ 6.00
Equity instruments expiration period														10 years	10 years
Equity instruments payment as a percentage of fair market value of outstanding equity														0.001%	0.001%
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional units available for grant													750,000
Increase in authorized shares as a percentage of common stock issued													1.50%
Shares authorized for issuance													1,801,180	1,125,000
Share based compensation, options granted		10,594
Stock compensation expense | $													$ 0	$ 0
Maximum payroll deduction													10.00%
Offering period													27 months
Amount divided by market price to determine number of shares | $													$ 2,083
Percentage of fair market value of common stock													85.00%
Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit price | $ / shares													$ 3.62	$ 5.35
Class A [Member] | 2011 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent available to grant out of outstanding units							7.50%
Class A [Member] | 2016 Equity Incentive Plan [Member] | January 2015 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price | $ / shares																		$ 6.00
Other Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants exercise price | $ / shares				$ 4.50												$ 138.06			$ 21.24
Expected dividend yield													0.00%
Expected life													3 months 7 days
Risk-free interest rate													1.39%
Volatility													71.50%
2015 Credit Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of Warrant or Right, Outstanding													617,651
Warrants exercise price | $ / shares													$ 10.20			$ 10.20
2015 Credit Agreement [Member] | Secured Term Debt [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants exercise price | $ / shares													$ 10.20
Minimum [Member] | 2016 Equity Incentive Plan [Member] | July 2016 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period													1 year
Minimum [Member] | 2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of hours per week for eligibility													20 hours
Number of months employed for eligibility													5 months
Percentage of ownership of stock or options													5.00%
Rate of yearly ownership value | $													$ 25,000
Number of shares for ESPP for offering period													200
Maximum [Member] | 2016 Equity Incentive Plan [Member] | July 2016 Modification [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period													3 years
2017 Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants issued		1,800,000	8,910,000										10,710,000
Warrants exercise price | $ / shares													$ 3.35
Warrant exercise price term													5 years
2017 Private Placement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants issued				2,707,138									2,707,138
Warrants exercise price | $ / shares				$ 4.50									$ 4.50
Warrant exercise price term				13 months									13 months