Stock-Based Compensation	6 Months Ended
Stock-Based Compensation	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation Long Term Incentive Compensation Plans The Company’s 2018 Long Term Incentive Compensation Plan (the “2018 Plan”) permits it to issue stock options (incentive and/or non-qualified), stock appreciation rights (“SARs”), restricted stock, phantom stock units (“PSUs”) and other equity and cash awards to employees. Non-employee directors are eligible to receive all such awards, other than incentive stock options. Prior to the 2018 Plan, the Company had the 2008 Long Term Incentive Compensation Plan (the “2008 Plan”), which expired in June 2018. Although awards can no longer be granted under the 2008 Plan, it remains in place until all of the awards previously granted thereunder have been paid, forfeited or expired. As of June 30, 2019, there were 9,421,571 shares available for future grants under the 2018 Plan. Share Repurchase Program On January 9, 2019, the Company announced a share repurchase program pursuant to which the Board of Directors authorized to repurchase up to $200 million of the Company’s common stock, which expires on December 31, 2020. During the six months ended June 30, 2019, the Company repurchased 1,271,823 shares of its common stock in open market transactions for $24.9 million at an average price of $19.55 per share. All repurchased shares were retired. Performance Share Program On February 14, 2019, the Company’s Compensation Committee of the Board of Directors adopted a performance share program (the “Performance Share Program II”) pursuant to the 2018 Plan, which provides for the issuance of restricted stock awards with performance-based vesting conditions. An aggregate of 278,780 performance shares, at target, was granted on February 14, 2019, with the grant having a three-year award period consisting of three one-year performance periods and a three-year service period. The performance threshold for vesting of these awards is 50% of target and, based on the level of achievement, up to 150% of target. Stock Options The Company granted 1,314,210 and 661,175 stock options during the six months ended June 30, 2019 and 2018, respectively. Stock-based Compensation Expense Stock-based compensation expense, which pertains to our stock options, restricted stock, and other equity awards, for the three and six months ended June 30, 2019 was $3.3 million and $6.7 million, respectively, as compared to $3.0 million and $5.9 million for the three and six months ended June 30, 2018, respectively, and is included within the unaudited Condensed Consolidated Statements of Operations under “General and administrative.” Stock Appreciation Rights The fair value of SARs is calculated each reporting period and estimated using the Black-Scholes option pricing model. The Company’s SARs, which vest over a period of four years, are accounted for as liability awards since they will be settled in cash. Accordingly, the Company has a liability, which is included in “Accrued expenses and other current liabilities” within the unaudited Condensed Consolidated Balance Sheets, associated with its SARs of $7.5 million and $6.8 million as of June 30, 2019 and December 31, 2018, respectively. For SARs held by employees of the Company, there was $7.4 million of total unrecognized compensation cost as of June 30, 2019 that will be recognized over the awards remaining weighted average vesting period of 2.79 years. For the three and six months ended June 30, 2019, the Company recognized a reduction to compensation expense of $0.5 million and compensation expense of $2.5 million, respectively, as compared to compensation expense of $9.8 million and $5.8 million for the three and six months ended June 30, 2018, respectively, associated with these awards. Compensation expense associated with our SARs is recorded in “General and administrative” within the unaudited Condensed Consolidated Statements of Operations. The Company paid $1.8 million and $4.5 million during the six months ended June 30, 2019 and 2018, respectively, pertaining to its cash-settled SARs. Phantom Stock Units The Company’s PSUs, which vest over a period of three to four years, entitle employees and directors to receive cash based on the fair value of the Company’s common stock on the vesting date. The PSUs are accounted for as liability awards and are re-measured at fair value each reporting period until they become vested with compensation expense being recognized over the requisite service period. The Company has a liability, which is included in “Accrued expenses and other current liabilities” within the unaudited Condensed Consolidated Balance Sheets, associated with its PSUs of $0.8 million and $1.7 million as of June 30, 2019 and December 31, 2018, respectively. For PSUs held by employees and directors of the Company, there was $3.8 million of total unrecognized compensation cost as of June 30, 2019 that will be recognized over the awards remaining weighted average vesting period of 2.04 years. For the three and six months ended June 30, 2019, the Company recognized $0.5 million and $1.6 million, respectively, of compensation expense associated with these awards, as compared to $1.4 million and $1.5 million, for the three and six months ended June 30, 2018, respectively. Compensation expense associated with our PSUs is recorded in “General and administrative” within the unaudited Condensed Consolidated Statements of Operations. The Company paid $2.5 million and $4.2 million during the six months ended June 30, 2019 and 2018, respectively, pertaining to its cash-settled PSUs.