Current and Long-Term Debt - Carrying Value, Convertible Notes (Details) - Convertible Senior Notes 1.00 percent due December 2020 - USD ($)	Jun. 30, 2020	Nov. 19, 2013	Sep. 30, 2020	Dec. 31, 2019
Long-Term Debt
Principal balance			$ 115,568,000	$ 287,500,000
Unamortized discount and capitalized debt issuance costs			(874,000)	(11,797,000)
Net carrying amount of Convertible Notes			$ 114,694,000	275,703,000
Conversion price (in dollars per share)		$ 52.35
Adjusted conversion price (in dollars per share)			$ 73.29
Aggregate principle amount		$ 287,500,000	$ 115,600,000	$ 287,500,000
Settlement amount	$ 1,000,000.0
Common Share Warrants
Long-Term Debt
Number of shares that may be purchased under warrant (in shares)			5,500,000
Warrant strike price (in dollars per share)			$ 73.29
Warrants outstanding (in shares)			2,200,000
Call Option
Long-Term Debt
Number of shares that may be acquired under call option (in shares)	2,200,000	5,500,000
Call option strike price (in dollars per share)	$ 52.35	$ 52.35