Borrowings - Additional Information (Details)			3 Months Ended
	Oct. 01, 2018 USD ($) $ / shares	Nov. 21, 2017 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Jul. 02, 2018 USD ($)
Credit Facilities [Line Items]
Interest coverage ratio, minimum			3.5
Leverage ratio, maximum			3.0
Long-term debt, maturities, repayments of principal in next twelve months			$ 20,000,000
Payment of debt issuance costs			97,000	$ 0
Allocation of equity component related to issuance costs on convertible senior notes			(13,000)
Debt discount amortization			600,000	$ 0
Structured payable			337,542,000
Current portion of long-term borrowings			20,876,000		$ 21,423,000
Long term borrowings			299,765,000		263,241,000
Notes Payable, Other Payables
Credit Facilities [Line Items]
Structured payable			1,542,000		2,114,000
Current portion of long-term borrowings			876,000		1,423,000
Long term borrowings			666,000		691,000
3.50% Convertible Senior Notes due October 1, 2024 | Convertible Notes Payable
Credit Facilities [Line Items]
Debt instrument face amount	$ 150,000,000
Interest rate	3.50%
Interest expense			1,313,000
Conversion rate	0.0133333000
Debt instrument, conversion price (in dollars per share) | $ / shares	$ 75
Threshold percentage of stock price trigger	150.00%
Net proceeds from convertible notes	$ 149,000,000
Debt issuance costs	1,000,000
Payment of debt issuance costs	442,000
Liability component of debt issuance costs	1,279,000
Equity component of debt issuance costs	163,000
Unamortized debt issuance costs			1,178,000		$ 1,127,000
Convertible notes, liability component	133,077,000
Convertible senior notes, interest rate					5.75%
Allocation of equity component related to issuance costs on convertible senior notes	$ 16,923,000
Remaining discount amortization period	6 years
Debt discount amortization	$ 600,000
Structured payable			150,000,000		$ 150,000,000
Revolving Credit Facility
Credit Facilities [Line Items]
Outstanding debt			186,000,000		150,000,000
Outstanding debt, noncurrent			166,000,000		130,000,000
Outstanding debt, current					20,000,000
Unamortized debt issuance costs			942,000		$ 1,006,000
Repayments of outstanding borrowings	$ 150,000,000
Structured payable			$ 186,000,000
Revolving Credit Facility | New Credit Agreement
Credit Facilities [Line Items]
Maximum borrowing capacity		$ 200,000,000
Line of credit interest rate during period			3.90%	3.30%
Unrestricted domestic cash and cash equivalents threshold			$ 50,000,000
Interest coverage ratio, minimum			3.5
Leverage ratio, maximum			3.0
Revolving Credit Facility | New Credit Agreement | Maximum
Credit Facilities [Line Items]
Commitment fee percentage range on unused credit facility		0.30%
Revolving Credit Facility | New Credit Agreement | Minimum
Credit Facilities [Line Items]
Commitment fee percentage range on unused credit facility		0.15%
Revolving Credit Facility | New Credit Agreement | Prime Rate | Maximum
Credit Facilities [Line Items]
Basis spread on variable rate		0.75%
Revolving Credit Facility | New Credit Agreement | Prime Rate | Minimum
Credit Facilities [Line Items]
Basis spread on variable rate		0.00%
Revolving Credit Facility | New Credit Agreement | London Interbank Offered Rate (LIBOR) | Maximum
Credit Facilities [Line Items]
Basis spread on variable rate		1.75%
Revolving Credit Facility | New Credit Agreement | London Interbank Offered Rate (LIBOR) | Minimum
Credit Facilities [Line Items]
Basis spread on variable rate		1.00%
SCIO | Revolving Credit Facility | New Credit Agreement
Credit Facilities [Line Items]
Maximum borrowing capacity						$ 300,000,000
SCIO | Revolving Credit Facility | New Credit Agreement | Maximum
Credit Facilities [Line Items]
Option to increase additional credit facility						$ 100,000,000