Debt (Narrative) (Details)										1 Months Ended	12 Months Ended
	Jan. 25, 2021 USD ($) shares	Oct. 01, 2020 USD ($) shares	Jul. 01, 2020 USD ($)	Apr. 01, 2020 USD ($)	Jan. 02, 2020 USD ($)	Nov. 06, 2019 USD ($) yr	Oct. 12, 2018	May 17, 2018 USD ($) yr shares $ / shares	Jan. 16, 2018 USD ($) yr Month shares day $ / shares	Jun. 30, 2019 USD ($)	Dec. 31, 2020 USD ($) yr	Dec. 31, 2019 USD ($) yr	Dec. 31, 2018 USD ($)	Feb. 01, 2021	Jan. 30, 2020	Aug. 06, 2019 USD ($)	Apr. 03, 2019 shares	Jan. 30, 2019	Nov. 13, 2018 USD ($)	Aug. 08, 2018 USD ($)
Schedule of Capitalization, Long-term Debt [Line Items]
Proceeds from borrowings on senior secured convertible notes (related party)											$ 0	$ 0	$ 100,000,000
Interest paid											23,792,000	4,081,000	8,136,000
Debt issuance costs											0	0	5,146,000
Amortization of deferred issuance costs											1,560,000	1,078,000	955,000
Accretion of debt discount											7,571,000	6,242,000	4,812,000
Current financing lease liability											1,922,000
Remaining future minimum payment											1,108,000
Recurring
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability											15,002,000	29,312,000
Level 2 | Recurring
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability											0	0
Level 3 | Interest Make-whole Derivative Liability
Schedule of Capitalization, Long-term Debt [Line Items]
Estimated value of the interest make-whole derivative											871,000	0	0
Level 3 | Recurring
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability											15,002,000	29,312,000
Wells Fargo Bank, N.A. | Letter of credit
Schedule of Capitalization, Long-term Debt [Line Items]
Letters of credit outstanding											3,300,000
Convertible senior notes
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note											204,000,000	204,000,000
Debt issuance discount											9,498,000	17,068,000
Amortization of deferred issuance costs											1,200,000	1,100,000
Accretion of debt discount											7,600,000	6,200,000
Convertible senior notes | Level 3
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes											191,800,000
Convertible senior notes | Initial Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note											$ 153,500,000	$ 153,500,000
Stated interest rate											12.00%	12.00%
Debt issuance discount											$ 8,200,000	$ 14,703,000
Convertible senior notes | Option Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note											$ 50,500,000	$ 50,500,000
Stated interest rate											12.00%	12.00%
Debt issuance discount											$ 1,298,000	$ 2,365,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note									$ 150,000,000.0										$ 2,000,000.0
Proceeds from borrowings on senior secured convertible notes (related party)									$ 85,000,000.0
Converted shares issued (in shares) | shares									2,600,000
Value of amount of shares of common stock									$ 65,000,000.0
Share price (in dollars per share) | $ / shares									$ 24.45
Debt issuance discount at inception of notes									$ 1,400,000
Right to increase borrowing									$ 50,000,000.0
Number of shares callable by warrants (in shares) | shares									250,000								323,448
Conversion price, percentage premium of trading price									30.00%
Conversion threshold, consecutive trading days | day									10
Conversion price (in dollars per share) | $ / shares									$ 31.29
Stated interest rate									6.00%
Debt issuance discount									$ 20,100,000
Quarterly interest paid			$ 6,100,000	$ 6,100,000	$ 6,100,000
Accrued interest											6,100,000
Issuance of PIK Interest Shares (in shares) | shares		1,474,201
Interest paid		$ 3,100,000
Price of warrants (in dollars per share) | $ / shares									$ 0.01
Exercisable period of warrants							5 years
Debt issuance costs									$ 4,600,000
Derivative liability						$ 600,000													200,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Subsequent event
Schedule of Capitalization, Long-term Debt [Line Items]
Quarterly interest paid	$ 6,100,000
Issuance of PIK Interest Shares (in shares) | shares	2,802,454
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Conversion price (in dollars per share) | $ / shares									$ 28.00
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Stated interest rate															12.00%			12.00%
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Maximum | Subsequent event
Schedule of Capitalization, Long-term Debt [Line Items]
Stated interest rate														12.00%
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Convertible Bond Model
Schedule of Capitalization, Long-term Debt [Line Items]
Share price (in dollars per share) | $ / shares									$ 24.45
Debt issuance discount									$ 6,400,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Convertible Bond Model | Credit Adjusting Discount Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.250
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Convertible Bond Model | Option Volatility
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.413
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Convertible Bond Model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.022
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Convertible Bond Model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr									4
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Option pricing model
Schedule of Capitalization, Long-term Debt [Line Items]
Share price (in dollars per share) | $ / shares									$ 24.45
Fair value of notes									$ 2,100,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Option pricing model | Option Volatility
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.384
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Option pricing model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.016
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Option pricing model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | Month									6
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes									$ 4,400,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.022
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Probability | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Probability | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.10
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr									4
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Black Scholes Model
Schedule of Capitalization, Long-term Debt [Line Items]
Share price (in dollars per share) | $ / shares									$ 24.45
Fair value of warrants									$ 6,100,000
Proceeds from the issuance of warrants									5,700,000
Adjustment to fair value of warrants allocated to additional paid in capital									$ 200,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Black Scholes Model | Dividend yield
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Black Scholes Model | Option Volatility
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.396
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Black Scholes Model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input									0.024
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Black Scholes Model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr									5
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Discounted Cash Flow Model
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes						$ 1,200,000
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Discounted Cash Flow Model | Credit Adjusting Discount Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input						0.250
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Discounted Cash Flow Model | Probability | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input						0
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Discounted Cash Flow Model | Probability | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input						0.05
Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022 | Discounted Cash Flow Model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr						0.7
Convertible senior notes | Starboard Value LP | Initial Notes
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note													204,000,000.0
Proceeds from borrowings on senior secured convertible notes (related party)													$ 100,000,000.0
Debt instrument, covenant, minimum cash balance											40,000,000.0
Convertible senior notes | Starboard Value LP | Additional Notes Issued August 8, 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note																				$ 2,000,000.0
Convertible senior notes | Starboard Value LP | Additional Initial Notes
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note																				1,500,000
Derivative liability																				200,000
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note								$ 50,000,000.0
Proceeds from borrowings on senior secured convertible notes (related party)								$ 15,000,000.0
Converted shares issued (in shares) | shares								1,400,000
Value of amount of shares of common stock								$ 35,000,000.0
Share price (in dollars per share) | $ / shares								$ 21.75
Debt issuance discount at inception of notes								$ 4,600,000
Debt issuance discount								3,100,000
Debt issuance costs								$ 200,000
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Convertible Bond Model
Schedule of Capitalization, Long-term Debt [Line Items]
Share price (in dollars per share) | $ / shares								$ 21.75
Fair value of notes								$ 3,000,000.0
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Convertible Bond Model | Credit Adjusting Discount Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.24
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Convertible Bond Model | Option Volatility
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.426
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Convertible Bond Model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.028
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Convertible Bond Model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr								3.7
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Option pricing model
Schedule of Capitalization, Long-term Debt [Line Items]
Share price (in dollars per share) | $ / shares								$ 21.75
Fair value of notes								$ 5,700,000
Debt issuance premium								$ 1,600,000
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Option pricing model | Option Volatility
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.263
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Option pricing model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.018
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Option pricing model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr								0.16
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes								$ 1,200,000
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Risk-free Rate
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.028
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Probability | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Probability | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input								0.10
Convertible senior notes | Starboard Value LP | Option Notes, due January 16, 2022 | Probability-adjusted Binomial Lattice Model | Term
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr								3.7
Convertible senior notes | Starboard Value LP | Additional Option Notes
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note																				$ 500,000
Convertible senior notes | Starboard Value LP | Right Offering Notes
Schedule of Capitalization, Long-term Debt [Line Items]
Maximum percentage exchangeable for common stock									30.00%
Debt term									4 years
Conversion price percentage									130.00%
Backstop commitment by third party									$ 100,000,000.0
Backstop reduced by the amount of option notes purchased									$ 50,000,000.0
Convertible senior notes | Starboard Value LP | Right Offering Notes | Minimum
Schedule of Capitalization, Long-term Debt [Line Items]
Conversion price (in dollars per share) | $ / shares									$ 28.00
Convertible senior notes | Starboard Value LP | Right Offering Notes | Maximum
Schedule of Capitalization, Long-term Debt [Line Items]
Additional borrowing option									$ 150,000,000.0
Secured Term Note | Secured Term Note
Schedule of Capitalization, Long-term Debt [Line Items]
Face value of note											$ 13,000,000	$ 13,000,000
Stated interest rate											9.75%	9.75%
Debt instrument, covenant, minimum cash balance											$ 14,800,000
Amortization of deferred issuance costs											300,000
Secured Term Note | Secured Term Note | Level 3
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes											13,400,000
Debt covenant, period one | Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, covenant, minimum cash balance						$ 20,000,000.0
Debt covenant, period one | Convertible senior notes | Starboard Value LP | Initial Notes
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, covenant, minimum cash balance																			$ 20,000,000.0
Debt covenant, period two | Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, covenant, minimum cash balance						$ 40,000,000.0
Debt instrument, covenant, premium on qualifying change of control						20.00%
Debt covenant, period two | Convertible senior notes | Starboard Value LP | Initial Notes
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, covenant, minimum cash balance									$ 40,000,000.0							$ 40,000,000.0
Failed Sale Leaseback Transaction
Schedule of Capitalization, Long-term Debt [Line Items]
Sale leaseback transaction, proceeds from the failed sale of the assets										$ 4,300,000
Sale leaseback transaction, term of contract										24 months
Sale leaseback transaction, total consideration										$ 4,800,000
Current financing lease liability											1,700,000
Remaining future minimum payment											$ 1,400,000
Make-whole change of control redemption | Option pricing model | Risk-free Rate | Level 3
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input											0	0.016
Make-whole change of control redemption | Option pricing model | Term | Level 3
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr											0	2.04
Make-whole change of control redemption | Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes						$ 2,200,000
Combined value of the make-whole and qualifying change of control redemption | Convertible senior notes | Starboard Value LP | Initial Notes, due January 16, 2022
Schedule of Capitalization, Long-term Debt [Line Items]
Fair value of notes						$ 2,800,000
Interest Make-whole Derivative Liability | Discounted Cash Flow Model | Risk-free Rate | Level 3
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input											0.0010	0
Interest Make-whole Derivative Liability | Discounted Cash Flow Model | Term | Level 3
Schedule of Capitalization, Long-term Debt [Line Items]
Derivative liability, measurement input | yr											0.25	0