Debt (Detail Textuals 1)	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 25, 2017 USD ($) $ / shares	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Day	Jun. 30, 2016 USD ($)
Debt Instrument [Line Items]
Proceeds from sale of convertible senior notes				$ 84,866,000
Amount of conversion premium convertible senior notes				2,520,000
Interest expense		$ 9,293,000	$ 6,063,000	16,944,000	$ 11,050,000
Amortization of discount and deferred expenses				(111,000)
Convertible Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount of Convertible Senior Notes	$ 87,500,000
Interest rate	7.25%
Frequency of interest payment	quarterly
Due date	Apr. 30, 2024
Proceeds from sale of convertible senior notes	$ 84,900,000
Amount of conversion premium convertible senior notes	$ 2,500,000
If-converted value in excess of principal				$ 8,000
Threshold percentage of stock price trigger				130.00%
Threshold trading days | Day				20
Threshold consecutive trading days | Day				30
Value of unpaid principal balance of note		87,500,000		$ 87,500,000
Amount of discount and deferred expenses		$ 5,400,000		5,400,000
Interest expense				1,300,000
Amortization of discount and deferred expenses				$ 100,000
Effective rate of interest on notes		8.90%		8.90%
Conversion premium on notes		17.50%		17.50%
Convertible Senior Notes | Common Stock
Debt Instrument [Line Items]
Conversion rate	1.6267
Debt instrument convertible principal amount per share | $ / shares	$ 25.00
Conversion price per share | $ / shares	$ 15.37