CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
CONSOLIDATED STATEMENTS OF INCOME
Rental income from a lessee that qualifies as a related party	$ 1,095	$ 1,068	$ 2,181	$ 2,127
Straight-line rental income from a lessee that qualifies as a related party	31	57	70	123
Interest income from an entity that qualifies as a related party	$ 55	$ 180	$ 235	$ 360