Credit Facilities (Details)				1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 03, 2016 shares	Nov. 02, 2015 USD ($) $ / shares	Dec. 10, 2013 USD ($) $ / shares $ / securities	Feb. 29, 2016 USD ($)	Mar. 31, 2016 USD ($) d $ / shares	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Jul. 21, 2015 USD ($)
Line of Credit Facility [Line Items]
Convertible notes					$ 170,028,000		$ 167,748,000
Payments of derivative issuance costs			$ 7,400,000
Change in fair value of derivative liabilities					$ 5,088,000	$ 0
Revolving Credit Facility | Bank of America
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity								$ 20,000,000
Minimum current ratio					1.5
Letter of Credit | Bank of America
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity								$ 10,000,000
Convertible Debt
Line of Credit Facility [Line Items]
Reclassification of conversion features to derivative liabilities				$ 24,800,000
2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Debt instrument face amount			86,250,000
Stated interest rate					2.25%		2.25%
Proceeds from convertible debt			82,600,000
Conversion of convertible securities					41.6051
Redemption price percentage					100.00%
Violation or event of default, declaration by note holders, percentage					25.00%
Fair value disclosure							$ 66,900,000
Beneficial conversion feature							19,300,000
Unamortized discount							3,700,000
Convertible notes			$ 86,300,000		$ 74,900,000
Deferred finance costs, noncurrent, net					$ 1,800,000
Convertible conversion price | $ / shares			$ 24.04		$ 24.04
Cap price | $ / securities			29.02
3.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Debt instrument face amount		$ 125,000,000.0
Stated interest rate					3.25%
Threshold trading days | d					20
Threshold consecutive trading days					30 days
Threshold consecutive business days					5 days
Threshold percentage of stock price trigger					130.00%
Threshold business days | d					5
Conversion of convertible securities		89.4314
Redemption price percentage		98.00%			100.00%
Fair value disclosure		$ 97,800,000
Beneficial conversion feature		27,200,000
Unamortized discount		2,900,000
Convertible notes		$ 125,000,000			$ 99,600,000
Deferred finance costs, noncurrent, net					$ 2,700,000
Convertible conversion price | $ / shares		$ 11.18
Redemption, Period One | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Threshold trading days | d					20
Threshold consecutive trading days					30 days
Threshold percentage of stock price trigger					130.00%
Redemption price percentage					100.00%
Redemption, Period Two | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Threshold trading days | d					20
Threshold consecutive trading days					5 years
Threshold consecutive business days					30 days
Threshold percentage of stock price trigger					98.00%
Threshold business days | d					5
Other Assets | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Unamortized discount							2,900,000
Other Assets | 3.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Unamortized discount		$ 3,700,000
Additional Paid-in Capital | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Unamortized discount							800,000
Additional Paid-in Capital | 3.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Unamortized discount		$ 800,000
Minimum | Revolving Credit Facility | Bank of America
Line of Credit Facility [Line Items]
Liquidation proceeds, monetary amount					$ 30,000,000
Unencumbered liquid assets, cash conversion period					5 days
Minimum | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Periodic interest payment					$ 5,700,000
Minimum | 3.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Periodic interest payment					9,100,000
Maximum | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Periodic interest payment					6,900,000
Maximum | 3.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Periodic interest payment					10,700,000
Accounting Standards Update 2015-03 | Other Assets | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Debt issuance costs, net							(1,900,000)
Accounting Standards Update 2015-03 | Other Assets | 3.25% Convertible Senior Notes
Line of Credit Facility [Line Items]
Debt issuance costs, net					$ (2,900,000)
Accounting Standards Update 2015-03 | Long-term Debt | 2.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Debt issuance costs, net							1,900,000
Accounting Standards Update 2015-03 | Long-term Debt | 3.25% Convertible Senior Notes | Convertible Debt
Line of Credit Facility [Line Items]
Debt issuance costs, net							$ 2,900,000
TriVascular Technologies, Inc.
Line of Credit Facility [Line Items]
Equity consideration issued in merger (in shares) | shares	13,586,503