Company Unit Options (Summary of Partnership Unit Option) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Unit Option [Member]
Share Based Compenstation Arrangement By Share Based Payment Award Unit Option [Abstract]
Outstanding, beginning of period	349,018
Exercised	(70,278)
Foreited	(2,681)
Outstanding, end of period	276,059
Options exercisable at beginning of period	276,059
Unit Options Weighted Average Share Price [Abstract]
Outstanding, beginning of period	$ 7.25
Excercised	$ 5.70
Forfeited	$ 26.75
Outstanding, End of period	$ 7.46
Weighted Average Contractual Term End Of Period [Abstract]
Options outstanding	5 years 11 months
Options excercisable	5 years 11 months
Aggregate Instrinsic Value End Of Period [Abstract]
Options outstanding	$ 3,345
Options exerciseable	$ 3,345
Stock Options [Member]
Share Based Compenstation Arrangement By Share Based Payment Award Unit Option [Abstract]
Options exercisable at beginning of period	37,500	37,500
Unit Options Weighted Average Share Price [Abstract]
Outstanding, beginning of period	$ 6.50
Outstanding, End of period	$ 6.50
Weighted Average Contractual Term End Of Period [Abstract]
Options outstanding	1 year 7 months