Credit Facilities (Details) (USD $)	0 Months Ended	12 Months Ended			0 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended
	Dec. 10, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 03, 2013	Mar. 31, 2014	Jun. 30, 2014	Sep. 30, 2014	Mar. 31, 2015	Jun. 30, 2015	Sep. 30, 2015	Jun. 12, 2013	Feb. 03, 2015
Line of Credit Facility [Line Items]
Proceeds from convertible debt		$ 0	$ 86,250,000	$ 0
Amortization of debt issuance costs		0	(3,657,000)	0
Convertible notes		70,407,000	67,101,000
Payments of derivative issuance costs	7,400,000
Letters of credit outstanding, amount												5,400,000
Revolving Credit Facility | Wells Fargo Bank
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount		6,000,000
Debt covenant, minimum current ratio					2.0
Revolving Credit Facility | Wells Fargo Bank | Subsequent Event
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity													20,000,000
Revolving Credit Facility | Wells Fargo Bank | Year ended December 31, 2013
Line of Credit Facility [Line Items]
Debt covenant, maximum operating loss		40,000,000				11,000,000	18,000,000	22,000,000
Debt covenant, maximum capital expenditures		14,500,000	6,000,000
Debt covenant, maximum operating lease expenditures		3,000,000
Revolving Credit Facility | Wells Fargo Bank | Year ended December 31, 2013 | Forecast
Line of Credit Facility [Line Items]
Debt covenant, maximum operating loss									13,500,000	23,000,000	35,000,000
Revolving Credit Facility | Wells Fargo Bank | Prime Rate
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate		1.00%
Letter of Credit | Wells Fargo Bank
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		7,500,000.0
Convertible Senior Notes | 2.25% Convertible Senior Notes
Line of Credit Facility [Line Items]
Convertible notes, face amount	86,300,000
Convertible notes, stated percentage	2.25%
Proceeds from convertible debt	82,600,000
Stock Issued During Period, Shares, Conversion of Convertible Securities	41.6051
Debt instrument, dedemption price, percentage	100.00%
Convertible debt, conversion ratio	0.0416051
Convertible debt, conversion price	$ 24.04
Debt instrument, debt default, declaration by note holders, percentage	25.00%
Debt instrument, fair value	66,900,000
Debt instrument, embedded conversion option	19,300,000
Debt instrument, unamortized discount	3,700,000
Convertible notes		70,400,000
Deferred financing costs		2,400,000
Derivative, cap price	29.02
Convertible Senior Notes | 2.25% Convertible Senior Notes | Minimum
Line of Credit Facility [Line Items]
Estimated annual interest expense, debt		5,700,000
Convertible Senior Notes | 2.25% Convertible Senior Notes | Maximum
Line of Credit Facility [Line Items]
Estimated annual interest expense, debt		6,900,000
Convertible Senior Notes | 2.25% Convertible Senior Notes | Other Assets
Line of Credit Facility [Line Items]
Debt instrument, unamortized discount	2,900,000
Convertible Senior Notes | 2.25% Convertible Senior Notes | Additional Paid-in Capital
Line of Credit Facility [Line Items]
Debt instrument, unamortized discount	$ 800,000
Convertible Senior Notes | 2.25% Convertible Senior Notes | On or after December 15, 2016
Line of Credit Facility [Line Items]
Convertible debt redemption, trading days threshold	20
Convertible debt redemption, consecutive trading days threshold	30 days
Convertible debt redemption, percentage of stock price trigger, percentage	130.00%
Debt instrument, dedemption price, percentage	100.00%
Convertible Senior Notes | 2.25% Convertible Senior Notes | Business Day Immediately Preceding September 15, 2018
Line of Credit Facility [Line Items]
Convertible debt redemption, trading days threshold	20
Convertible debt redemption, consecutive trading days threshold	30 days
Convertible debt redemption, business days threshold	5
Convertible debt redemption, consecutive business days threshold	5 years
Convertible debt redemption, percentage of stock price trigger, percentage	130.00%
Debt instrument, dedemption price, percentage	98.00%