CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
CONSOLIDATED STATEMENTS OF INCOME
Rental income from a lessee that qualifies as a related party	$ 1,095	$ 1,068	$ 3,275	$ 3,196
Straight-line rental income from a lessee that qualifies as a related party	31	57	101	181
Interest income from an entity that qualifies as a related party		$ 180	$ 235	$ 540