SHAREHOLDERS’ EQUITY AND SHARE-BASED COMPENSATION Stock Repurchase Plan & Share-Based Compensation (Details) | May 15, 2018$ / sharesshares | Jun. 30, 2019USD ($)$ / sharesshares | Jun. 30, 2018USD ($)$ / sharesshares | Jun. 30, 2019USD ($)component$ / sharesshares | Jun. 30, 2018USD ($)$ / sharesshares | Dec. 31, 2018shares |
Share Repurchase Program | | | | | | |
Authorized amount (in dollars) | $ | | $ 105,000,000 | | $ 105,000,000 | | |
Capacity available to repurchase common stock under senior secured term loan (in dollars) | $ | | 467,000,000 | | 467,000,000 | | |
Share-Based Compensation | | | | | | |
Share-based compensation expense | $ | | 2,800,000 | $ 1,900,000 | 5,453,000 | $ 4,111,000 | |
Estimated unrecognized compensation costs (in dollars) | $ | | $ 14,600,000 | | $ 14,600,000 | | |
Weighted average remaining requisite service period for stock options over which unrecognized compensation costs would be recognized | | | | 1 year 8 months 19 days | | |
Outstanding (in shares) | | 1,562,705 | | 1,562,705 | | 1,440,566 |
Performance criteria achieved (in shares) | | | | 227,849 | | |
Weighted average fair value of stock options granted and total intrinsic value of stock options exercised | | | | | | |
Weighted average grant date fair value of stock options granted per share (in usd per share) | $ / shares | | | | $ 0 | $ 16.27 | |
Intrinsic value of options exercised | $ | | | | $ 34,000 | $ 4,393,000 | |
Grant date fair value of stock options that vested | $ | | | | $ 2,752,000 | $ 1,334,000 | |
Employee and non-employee stock options | | | | | | |
Share-Based Compensation | | | | | | |
Stock options granted (in shares) | | | | 0 | 272,000 | |
Weighted average exercise price of stock options granted (in usd per share) | $ / shares | | | | | $ 25.06 | |
Employee and non-employee stock options | Service-Based | | | | | | |
Share-Based Compensation | | | | | | |
Outstanding (in shares) | | 460,000 | | 460,000 | | |
Employee and non-employee stock options | Service-Based | Minimum | | | | | | |
Share-Based Compensation | | | | | | |
Share-based compensation arrangement by share-based payment award, award vesting period | | | | 3 years | | |
Employee and non-employee stock options | Service-Based | Maximum | | | | | | |
Share-Based Compensation | | | | | | |
Share-based compensation arrangement by share-based payment award, award vesting period | | | | 4 years | | |
Expiration term | | | | 10 years | | |
Employee and non-employee stock options | Market-Based | | | | | | |
Share-Based Compensation | | | | | | |
Outstanding (in shares) | | 600,000 | | 600,000 | | |
Number of components of an award | component | | | | 2 | | |
Allowable performance period before expiration date | | | | 3 years | | |
Employee and non-employee stock options | Market-Based | Minimum | | | | | | |
Share-Based Compensation | | | | | | |
Share-based compensation arrangement by share-based payment award, award vesting period | | | | 3 years | | |
Expiration term | | | | 10 years | | |
Employee and non-employee stock options | Market-Based | Maximum | | | | | | |
Share-Based Compensation | | | | | | |
Share-based compensation arrangement by share-based payment award, award vesting period | | | | 4 years | | |
Employee and non-employee stock options | Market-Based, ordinary performance | Minimum | | | | | | |
Share-Based Compensation | | | | | | |
Percentage of compounded annual gain of stock price over exercise price required for the award to vest | | | | 20.00% | | |
Employee and non-employee stock options | Market-Based, extraordinary performance | Minimum | | | | | | |
Share-Based Compensation | | | | | | |
Percentage of compounded annual gain of stock price over exercise price required for the award to vest | | | | 25.00% | | |
Employee and non-employee stock options | Performance-Based | | | | | | |
Share-Based Compensation | | | | | | |
Outstanding (in shares) | | 503,000 | | 503,000 | | |
Employee and non-employee stock options | Performance-Based | Minimum | | | | | | |
Share-Based Compensation | | | | | | |
Allowable performance period before expiration date | | | | 10 years | | |
Attainment above threshold performance levels, vesting percentage | | | | 50.00% | | |
Employee and non-employee stock options | Performance-Based | Maximum | | | | | | |
Share-Based Compensation | | | | | | |
Attainment above threshold performance levels, vesting percentage | | | | 200.00% | | |
Employee and non-employee stock options | Performance-Based, Vesting Period One | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 25.00% | | |
Employee and non-employee stock options | Performance-Based, Vesting Period Two | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 25.00% | | |
Employee and non-employee stock options | Performance-Based, Vesting Period Three | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 25.00% | | |
Employee and non-employee stock options | Performance-Based, Vesting Period Four | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 25.00% | | |
Restricted Stock And Restricted Stock Units (RSUs) | | | | | | |
Share-Based Compensation | | | | | | |
Restricted shares and restricted share units outstanding (in shares) | | 696,160 | | 696,160 | | 485,806 |
Restricted Stock And Restricted Stock Units (RSUs) | Service-Based | | | | | | |
Share-Based Compensation | | | | | | |
Alternate award vesting period | | | | 2 years | | |
Restricted shares and restricted share units outstanding (in shares) | | 546,000 | | 546,000 | | |
Restricted Stock And Restricted Stock Units (RSUs) | Service-Based | Minimum | | | | | | |
Share-Based Compensation | | | | | | |
Share-based compensation arrangement by share-based payment award, award vesting period | | | | 2 years | | |
Restricted Stock And Restricted Stock Units (RSUs) | Service-Based | Maximum | | | | | | |
Share-Based Compensation | | | | | | |
Share-based compensation arrangement by share-based payment award, award vesting period | | | | 4 years | | |
Restricted Stock And Restricted Stock Units (RSUs) | Performance-Based | | | | | | |
Share-Based Compensation | | | | | | |
Restricted shares and restricted share units outstanding (in shares) | | 150,000 | | 150,000 | | |
Restricted Stock And Restricted Stock Units (RSUs) | Performance-Based | Maximum | | | | | | |
Share-Based Compensation | | | | | | |
Attainment above threshold performance levels, vesting percentage | | | | 225.00% | | |
Restricted Stock And Restricted Stock Units (RSUs) | Performance-Based, Vesting Period One | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 33.00% | | |
Restricted Stock And Restricted Stock Units (RSUs) | Performance-Based, Vesting Period Two | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 33.00% | | |
Restricted Stock And Restricted Stock Units (RSUs) | Performance-Based, Vesting Period Three | | | | | | |
Share-Based Compensation | | | | | | |
Vesting percentage | | | | 33.00% | | |
Restricted Stock Units (RSUs) | | | | | | |
Share-Based Compensation | | | | | | |
Restricted share units granted (in shares) | | | | 392,579 | | |
Restricted share units granted, weighted average grant date fair value (in usd per share) | $ / shares | | | | $ 24.86 | | |
Share Repurchase Program, Current | | | | | | |
Share Repurchase Program | | | | | | |
Number of shares of common stock authorized to be purchased (in shares) | 4,300,000 | | | | | |
Percentage of outstanding shares authorized to be repurchased | 25.00% | | | | | |
Minimum purchase price authorized (in usd per share) | $ / shares | $ 1 | | | | | |
Maximum purchase price authorized (in usd per share) | $ / shares | $ 500 | | | | | |
Period that shares may be repurchased, from the date of approval | 5 years | | | | | |
Remaining number of shares available for repurchase under the plan (in shares) | | 3,100,000 | | 3,100,000 | | |
Share Repurchase Programs | | | | | | |
Share Repurchase Program | | | | | | |
Number of shares of common stock purchased (in shares) | | 300,000 | 400,000 | | 800,000 | |
Average purchase price per share (in usd per share) | $ / shares | | $ 21.89 | $ 27.14 | $ 21.89 | $ 27.39 | |
Black-Scholes | | | | | | |
Assumptions used to determine the fair value of options as of the grant date | | | | | | |
Expected dividend yield | | | | | 0.00% | |
Black-Scholes | Minimum | | | | | | |
Assumptions used to determine the fair value of options as of the grant date | | | | | | |
Risk-free interest rate (%) | | | | 2.66% | | |
Expected stock price volatility (%) | | | | 70.31% | | |
Expected option life (in years) | | | | 6 years | | |
Fair value | $ / shares | | 16.17 | | $ 16.17 | | |
Black-Scholes | Maximum | | | | | | |
Assumptions used to determine the fair value of options as of the grant date | | | | | | |
Risk-free interest rate (%) | | | | 2.98% | | |
Expected stock price volatility (%) | | | | 71.86% | | |
Expected option life (in years) | | | | 6 years 3 months | | |
Fair value | $ / shares | | 19.06 | | $ 19.06 | | |
Binomial | | | | | | |
Assumptions used to determine the fair value of options as of the grant date | | | | | | |
Expected dividend yield | | | | | 0.00% | |
Binomial | Minimum | | | | | | |
Assumptions used to determine the fair value of options as of the grant date | | | | | | |
Risk-free interest rate (%) | | | | 1.64% | | |
Expected stock price volatility (%) | | | | 71.81% | | |
Expected option life (in years) | | | | 2 years 6 months 22 days | | |
Fair value | $ / shares | | 14.67 | | $ 14.67 | | |
Binomial | Maximum | | | | | | |
Assumptions used to determine the fair value of options as of the grant date | | | | | | |
Risk-free interest rate (%) | | | | 2.83% | | |
Expected stock price volatility (%) | | | | 71.86% | | |
Expected option life (in years) | | | | 4 years 3 months 26 days | | |
Fair value | $ / shares | | $ 18.28 | | $ 18.28 | | |