STOCK OPTION ACTIVITY (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Number of options
Options outstanding beginning of year	6,296,709
Options granted	1,865,000
Options exercised	(1,502,294)
Options forfeited/cancelled	(49,043)
Options outstanding end of year	6,610,372
Options vested and exercisable end of year	2,681,891
Options expected to vest	3,613,916
Weighted-Average Exercise Price
Options outstanding beginning of year	$ 7.51
Options granted	$ 23.03
Options exercised	$ 3.90
Options forfeited/cancelled	$ 14.67
Options outstanding at end of year	$ 12.66
Options vested and exercisable end of year	$ 5.79
Options expected to vest	$ 17.17
Aggregate Intrinsic Value
Options outstanding at beginning of year	$ 66,682
Options granted	7,740
Options exercised	(34,973)
Options forfeited/cancelled	(614)
Options outstanding at end of year	95,983
Options vested and exercisable at end of year	57,366
Options expected to vest	$ 36,175