STOCKHOLDERS' EQUITY (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) schedule plan $ / shares shares	Jun. 30, 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		179,778		179,778
Number of equity incentive plans | plan			3
Granted (in shares) | shares			86,500
Fair value as of vest date of RSUs			$ 46,100,000	$ 57,400,000
Stock-based compensation	$ 30,585,000	$ 30,452,000	62,335,000	61,770,000
Capitalized stock-based compensation expense	$ 2,200,000	3,100,000	$ 4,500,000	4,900,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target vesting range	0.00%		0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target vesting range	200.00%		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	$ 200,000	$ 2,000,000.0	$ 4,400,000	$ 2,800,000
Granted (in shares) | shares	0	0
Weighted average grant date fair value (in USD per share) | $ / shares			$ 11.13	$ 17.64
Unrecognized compensation costs	$ 12,100,000		$ 12,100,000
Unrecognized compensation costs, period for recognition			2 years 2 months 12 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	257,400,000		$ 257,400,000
Unrecognized compensation costs, period for recognition			2 years 8 months 12 days
Stock-based compensation	$ 0		$ 0
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		$ 45.3125
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in USD per share) | $ / shares	$ 18.48	$ 26.12	$ 18.48	$ 26.12
Subscription rate of eligible compensation	15.00%		15.00%
Purchase price, percentage of fair market value			85.00%
Number of shares purchased (in shares) | shares			433,697	288,529
Stock-based compensation	$ 500,000	$ 600,000	$ 1,300,000	$ 1,300,000
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		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		$ 269,000,000.0
Stock repurchased (in shares) | shares				11,690,224
Stock repurchased, amount				$ 397,600,000
Stock repurchased and retired during period (in shares) | shares				11,510,446