Earnings (Loss) Per Share (Details)		12 Months Ended
	Mar. 27, 2018	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares	Apr. 06, 2018 USD ($)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive common stock instruments outstanding (shares)		8,167,000	7,352,000	7,313,000
Conversion ratio	0.0323428
Shares issued		0
Repurchase of common stock under Prepaid Forward contract (shares)		1,858,500
Shares issuable upon the release of warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive common stock instruments outstanding (shares)		0	0	416,000
Shares issuable upon the release of restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive common stock instruments outstanding (shares)		76,000	24,000	40,000
Shares issuable upon exercise of stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive common stock instruments outstanding (shares)		8,091,000	7,328,000	6,857,000
Maximum
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issued		5,500,000
Unsecured obligations | 2.50% Convertible notes due 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Long-term debt | $		$ 171,500,000			$ 116,600,000
Conversion multiple | $					$ 1,000