DEBT (Senior Unsecured Revolving Credit Facility) (Narrative) (Details) - Unsecured Senior Revolving Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Credit facility capacity	$ 750,000,000
Minimum [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	0.75%
Maximum [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	1.63%
LIBOR [Member]
Debt Instrument [Line Items]
Interest rate in excess of LIBOR	1.125%	1.125%
Letter of Credit [Member]
Debt Instrument [Line Items]
Credit facility capacity	$ 150,000,000