Senior Convertible Notes - Narrative (Details) $ / shares in Units, shares in Thousands			2 Months Ended	3 Months Ended
	Mar. 18, 2016 USD ($) $ / shares shares	Nov. 03, 2014 USD ($) $ / shares	Dec. 31, 2014 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Nov. 01, 2014 USD ($)
Debt Instrument [Line Items]
Accrued interest payable				$ 2,474,000	$ 1,988,000
Amortization of deferred financing costs				4,153,000				$ 617,000
Debt conversion amount				82,274,000				0
Common stock issued for interest on Notes				2,445,000				0
Debt conversion expense				25,615,000				0
Convertible Senior Notes Due 2019
Debt Instrument [Line Items]
Aggregate principal amount (in dollars)		$ 200,000,000
Interest rate (as a percent)		7.50%
Additional aggregate principal amount pertaining to the over-allotment option granted (in dollars)		$ 25,000,000
Net proceeds from offering (in dollars)		$ 187,300,000
Accrued interest expense				486,000	2,982,000	$ 2,747,000	$ 3,388,000	3,750,000
Accrued interest payable			$ 2,500,000	2,474,000	1,988,000	4,969,000	2,222,000	6,250,000
Conversion rate (as a percent)		0.3215434
Conversion price (in dollars per share) | $ / shares		$ 3.11
Notes balance			200,000,000	79,182,000	159,011,000	159,011,000	177,787,000	200,000,000	$ 200,000,000
Transactions costs									$ 12,700,000
Amortization of deferred financing costs	$ 3,600,000		$ 411,000	4,153,000	506,000	1,544,000	1,899,000	$ 617,000
Debt conversion amount	$ 79,800,000			$ 79,829,000		$ 18,776,000	22,213,000
Percent of principal converted	50.00%
Number of shares issued on conversion of debt (in shares) | shares	35,300
Number of shares issued on conversion price excluding share issued for accrued interest (in shares) | shares	25,700
Number of shares issued for accrued interest (in shares) | shares	872
Five day average conversion price for accrued interest (in dollars per share) | $ / shares	$ 2.81
Common stock issued for interest on Notes	$ 2,400,000
Interest payment on senior convertible debenture					$ 5,963,000		$ 7,416,000