STOCK-BASED COMPENSATION

3 Months Ended

Mar. 31, 2018

8.	STOCK-BASED COMPENSATION

The Company recognizes all share-based payments based upon their fair value. The Company grants restricted stock units subject to service, performance and/or market conditions. The Company’s policy is to recognize expense for awards that have service conditions only subject to graded vesting using the straight-line attribution method. The fair value of service and performance based units is based on the market price of a share of underlying common stock at the date of grant. The fair value of the market based units is based on a lattice valuation model. The amount of compensation costs related to restricted stock units and performance units not yet recognized was $22.7 million at March 31, 2018 for which the expense will be recognized through 2021.