Certain provisions of the partnership agreement 2 (Details) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Weighted Average Number Of Diluted Shares Outstanding	47,396	47,191	47,372	47,136