Company Unit Options (Summary of Partnership Unit Option) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Unit Option [Member]
Share Based Compenstation Arrangement By Share Based Payment Award Unit Option [Abstract]
Outstanding, beginning of period	451,574
Exercised	(69,773)
Foreited	(11,281)
Outstanding, end of period	370,520
Options exercisable at end of period	304,799
Unit Options Weighted Average Share Price [Abstract]
Outstanding, beginning of period	$ 6.99
Excercised	$ 5.03
Forfeited	$ 15.58
Outstanding, End of period	$ 7.11
Weighted Average Contractual Term End Of Period [Abstract]
Options outstanding	6 years 5 months
Options excercisable	6 years 2 months
Aggregate Instrinsic Value End Of Period [Abstract]
Options outstanding	$ 3,513
Options exerciseable	$ 2,896
Stock Options [Member]
Share Based Compenstation Arrangement By Share Based Payment Award Unit Option [Abstract]
Options exercisable at end of period	37,500
Unit Options Weighted Average Share Price [Abstract]
Outstanding, End of period	$ 6.50