SHARE-BASED COMPENSATION (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Weighted average grant date fair value
Share based compensation costs expense	$ 25,410	$ 28,557
Liability for cash-settled restricted stock units	7,675		$ 21,731
Restricted Stock Units (RSUs)
Weighted average grant date fair value
Tax benefits associated with share-based compensation expense	3,995	4,263
Fair value of restricted stock units vested	46,490	49,323
Unrecognized share-based compensation expense	$ 98,005	$ 104,947
Expected weighted average period associated with the recognition of unrecognized share-based compensation expense	2 years 8 months 12 days	2 years 8 months 12 days
Restricted Stock Units (RSUs) | Cash Settled
Weighted average grant date fair value
Liability for cash-settled restricted stock units	$ 7,675	$ 12,946
Performance Vesting Restricted Stock Units | Share Settled
Number of restricted stock units
Nonvested restricted stock units - beginning of period (in shares)	258
Granted (in shares)	97
Vested (in shares)	(27)
Forfeited (in shares)	0
Nonvested restricted stock units - end of period (in shares)	328
Weighted average grant date fair value
Nonvested restricted stock units - beginning of period (in usd per share)	$ 53.31
Granted (in usd per share)	62.26
Vested (in usd per share)	64.01
Forfeited (in usd per share)	0
Nonvested restricted stock units - end of period (in usd per share)	$ 55.09
Performance Vesting Restricted Stock Units | Cash Settled
Number of restricted stock units
Nonvested restricted stock units - beginning of period (in shares)	6
Granted (in shares)	0
Vested (in shares)	(6)
Forfeited (in shares)	0
Nonvested restricted stock units - end of period (in shares)	0
Service Based Restricted Stock Units | Share Settled
Number of restricted stock units
Nonvested restricted stock units - beginning of period (in shares)	1,273
Granted (in shares)	786
Vested (in shares)	(474)
Forfeited (in shares)	(40)
Nonvested restricted stock units - end of period (in shares)	1,545
Weighted average grant date fair value
Nonvested restricted stock units - beginning of period (in usd per share)	$ 54.32
Granted (in usd per share)	60.95
Vested (in usd per share)	55.25
Forfeited (in usd per share)	57.33
Nonvested restricted stock units - end of period (in usd per share)	$ 57.33
Service Based Restricted Stock Units | Cash Settled
Number of restricted stock units
Nonvested restricted stock units - beginning of period (in shares)	853
Granted (in shares)	1
Vested (in shares)	(322)
Forfeited (in shares)	(25)
Nonvested restricted stock units - end of period (in shares)	507