Long-term Debt (Key Assumptions Used to Value Warrants) (Details) - $ / shares	1 Months Ended
	Oct. 31, 2017	Mar. 31, 2018	Sep. 30, 2017
Class of Warrant or Right [Line Items]
Common share price on date of issuance (in USD per share)		$ 15.00	$ 15.00
Tranche 1 | Common Shares
Class of Warrant or Right [Line Items]
Exercise price (in USD per share)	$ 15.06
Common share price on date of issuance (in USD per share)	$ 14.39
Volatility	73.20%
Risk-free interest rate	2.15%
Expected dividend yield	0.00%
Contractual term (in years)	7 years
Tranche 2 | Common Shares
Class of Warrant or Right [Line Items]
Exercise price (in USD per share)	$ 18.82
Common share price on date of issuance (in USD per share)	$ 18.96
Volatility	72.30%
Risk-free interest rate	2.78%
Expected dividend yield	0.00%
Contractual term (in years)	7 years