Long-Term Debt - Convertible Senior Notes (Details)
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3 Months Ended |
9 Months Ended |
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May 05, 2015
$ / shares
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Sep. 30, 2016
USD ($)
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Sep. 30, 2015
USD ($)
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Sep. 30, 2016
USD ($)
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Sep. 30, 2015
USD ($)
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| Carrying amount of Notes on the balance sheet: |
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| Interest expense |
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$ 3,565,093
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$ 3,414,826
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$ 10,592,654
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$ 7,803,050
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| Senior convertible notes, including interest |
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| Debt Instrument [Line Items] |
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| Stated interest rate |
2.50%
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| Conversion ratio |
25.5428
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| Conversion price (in usd per share) | $ / shares |
$ 39.15
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| Carrying amount of Notes on the balance sheet: |
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| Convertible senior notes, principal amount |
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230,000,000
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230,000,000
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| Unamortized debt discount |
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(23,546,293)
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(23,546,293)
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| Unamortized debt issuance costs |
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(4,656,966)
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(4,656,966)
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| Convertible senior notes, net |
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201,796,741
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201,796,741
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| Convertible senior notes, fair value |
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216,200,000
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216,200,000
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| Interest expense |
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9,400,000
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5,000,000
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| Contractual coupon interest |
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4,300,000
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2,300,000
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| Debt discount amortization |
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4,300,000
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2,300,000
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| Amortization of debt issuance costs |
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|
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$ 800,000
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$ 400,000
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| Senior convertible notes, including interest | Level 2 |
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| Debt Instrument [Line Items] |
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| Straight debt borrowing rate |
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5.75%
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| Fair value of liability component |
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198,500,000
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$ 198,500,000
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| Fair value of equity component |
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$ 31,500,000
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$ 31,500,000
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| Discount amortization period |
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5 years
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| Effective interest rate |
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6.33%
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6.33%
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