SHARE INCENTIVE PLANS: (Details) (Share options, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Share options
Stock option activity under equity incentive plans
Options outstanding at the beginning of the period (in shares)	2,467,523
Options exercised (in shares)	(71,214)
Options cancelled (in shares)	(16,105)
Options outstanding at the end of the period (in shares)	2,380,204
Weighted average exercise price of options outstanding
Options outstanding at the beginning of the period (in dollars per share)	$ 29.55
Options exercised (in dollars per share)	$ 17.60
Options cancelled (in dollars per share)	$ 75.38
Options outstanding at the end of the period (in dollars per share)	$ 29.59
Total pretax intrinsic value of options exercised	$ 2.0	$ 1.4
Closing price of ordinary shares (in dollars per share)	$ 45.34
Total pretax intrinsic value of all outstanding options	54.5
Total pretax intrinsic value of all exercisable options	$ 53.3		$ 50.1