SUBSEQUENT EVENT (Details) (Senior Notes, Subsequent Event, USD $)	0 Months Ended
	Apr. 30, 2015	Apr. 30, 2015
Senior Notes 2.67% Series A
Subsequent Event [Line Items]
Debt instrument, face amount	$ 200,000,000	$ 200,000,000
Stated interest rate	2.67%	2.67%
Debt instrument, term	7 years
Senior Notes 2.74% Series B
Subsequent Event [Line Items]
Debt instrument, face amount	$ 100,000,000	$ 100,000,000
Stated interest rate	2.74%	2.74%
Debt instrument, term	8 years