Consolidated Balance Sheets (Parenthetical)
Jun. 30, 2013
Dec. 31, 2012
Statement of Financial Position [Abstract]    
General partner's interest, units issued 35,750 35,750
General partner's interest, units outstanding 35,750 35,750
Limited partners' interest, units issued 35,713,700 35,713,700
Limited partners' interest, units outstanding 35,713,700 35,713,700