Long-Term Debt - Convertible Notes Interest and Carrying Value (Details) - Convertible Notes - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 01, 2016
Interest Expense, Debt [Abstract]
Cash interest per contractual coupon rate	$ 2,875	$ 2,875	$ 2,875
Amortization of note discount	11,341	10,762	10,210
Amortization of debt issuance costs	855	772	695
Total interest expense related to Convertible Notes	15,071	14,409	$ 13,780
Principal balance	287,500	287,500
Unamortized discount and capitalized debt issuance costs	(11,797)	(23,993)
Net carrying amount of Convertible Notes	$ 275,703	$ 263,507
Conversion price (in dollars per share)	$ 52.35			$ 52.35
Adjusted conversion price (in dollars per share)	$ 73.29
Common Share Warrants
Interest Expense, Debt [Abstract]
Number of shares that may be purchased under warrant	5.5
Warrant strike price (in dollars per share)	$ 73.29
Call Option
Interest Expense, Debt [Abstract]
Number of shares that may be acquired under call option	5.5
Call option strike price (in dollars per share)	$ 52.35