STOCKHOLDERS' EQUITY (Narrative) (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) schedule plan $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Jan. 31, 2020 USD ($)	Feb. 11, 2019 USD ($)	Nov. 27, 2018 USD ($)	Jul. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury stock (in shares) | shares	0
Number of equity incentive plans | plan	3
Fair value of vested shares	$ 29,100,000	$ 31,800,000
Stock-based compensation	31,750,000	31,319,000
Capitalized stock-based compensation expense	$ 2,300,000	1,800,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Vesting Range	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Vesting Range	200.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vesting schedules | schedule	4
Exercisable period	10 years
Intrinsic value of options exercised	$ 4,200,000	$ 800,000
Weighted average grant date fair value (in USD per share) | $ / shares	$ 11.13	$ 17.64
Unrecognized compensation costs	$ 13,900,000
Unrecognized compensation costs, period for recognition	2 years 4 months 24 days
Employee Stock Option | Monthly Basis First Year Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	35.00%
Employee Stock Option | Monthly Basis Second Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	40.00%
Employee Stock Option | Monthly Basis Third Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	25.00%
Employee Stock Option | End of year one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	25.00%
Employee Stock Option | First year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	10.00%
Employee Stock Option | Second year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	20.00%
Employee Stock Option | Third year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	30.00%
Employee Stock Option | Fourth year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	40.00%
Employee Stock Option | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Employee Stock Option | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Number of vesting schedules | schedule	3
Unrecognized compensation costs	$ 303,900,000
Unrecognized compensation costs, period for recognition	2 years 10 months 24 days
RSUs | End of year one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	25.00%
RSUs | First year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	10.00%
RSUs | Second year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	20.00%
RSUs | Third year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	30.00%
RSUs | Fourth year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate	40.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance goal stock price at which Performance Restricted Stock Unit awards would vest (usd per share) | $ / shares	$ 45.3125
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Subscription rate of eligible compensation	15.00%
Purchase price, percentage of fair market value	85.00%
Number of shares purchased (in shares) | shares	0	0
Stock-based compensation	$ 800,000	$ 700,000
July 2017 Share Repurchase Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount	950,000,000.0		$ 250,000,000.0	$ 250,000,000.0	$ 250,000,000.0	$ 200,000,000.0
Remaining authorized repurchase amount	$ 269,000,000.0
Stock repurchased and retired during period (in shares) | shares		2,847,226
Stock repurchased, amount		$ 102,100,000