Convertible 3.75% Senior Notes (Details Textual) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014		Dec. 22, 2014	Dec. 16, 2014
Debt Instrument [Line Items]
Payments of Debt Issuance Costs	$ 9,000
Derivative Liability	32,775,000
Derivative Liability, Fair Value, Gross Liability	32,775,000	41,400,000	[1]
Deferred Tax Liabilities, Deferred Expense, Deferred Financing Costs	4,600,000
Debt Instrument, Interest Rate, Stated Percentage	3.75%	3.75%
Convertible Notes Payable [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				18,750,000	125,000,000
Proceeds from Issuance of Senior Long-term Debt		139,000,000
Payments of Debt Issuance Costs		4,800,000
Interest Payable		1,600,000
Debt Instrument, Period of Debt Discount and Financing Costs Amortization	4 years 8 months 16 days
Debt Instrument, Convertible, Terms of Conversion Feature	The Notes are convertible at an initial conversion price of approximately $11.29 per share, which is equivalent to an initial conversion rate of 88.5716 shares per $1,000 principal amount of Notes, subject to adjustment in certain events, such as distributions of dividends or stock splits. Holders may convert their Notes at their option prior to September 15, 2019, when or if certain conditions have been met or circumstances have occurred, such as the Companys stock price exceeds 130% of the conversion price under the Notes for a designated period of time, or the trading price of the Notes is, for a designated period of time, less than 98% of the closing sale price of the Companys common stock multiplied by the then-current conversion rate of the Notes, or the Company calls Notes for redemption, or certain specified corporate events occur. Holders may also convert their Notes at their option at any time on or after September 15, 2019 and prior to the close of business on the business day immediately preceding the stated maturity date. In addition, following the occurrence of certain changes of control of the Company described in the Indenture governing the Notes or termination of trading of the Companys common stock or other securities into which the Notes are convertible (a make-whole fundamental change) or the delivery by the Company of a notice of redemption, the conversion rate for a holder who elects to convert its Notes in connection with such make-whole fundamental change or such notice of redemption will increase. Additionally, if certain conditions have been met or circumstances have occurred, such as the Companys stock price exceeds 150% of the conversion price under the Notes for a designated period of time, or the trading of the Notes is, for a designated period of time, less than 98% of the closing sale price of the Companys stock multiplied by the then-current conversion rate of the Notes, or the Company calls Notes for redemption, the Company may redeem for cash any or all outstanding Notes on or after December 19, 2017 in an amount equal to the outstanding principal amount of such Notes, plus accrued and unpaid interest.
Derivative Liability					43,700,000
Debt Instrument, Interest Rate, Effective Percentage					12.94%
Derivative Liability, Fair Value, Gross Liability	32,800,000
Increase (Decrease) in Derivative Liabilities	8,600,000
Convertible Notes Payable					$ 143,750,000
Debt Instrument, Interest Rate, Stated Percentage					3.75%

[1] *Derived from the audited December 31, 2014 financial statements