Accrued Liabilities (Schedule Of Accrued Liabilities) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accrued Liabilities [Abstract]
Accrued salaries, bonus, and benefits	$ 1,885,176	$ 2,123,167
Accrued rent	1,120,909	1,095,641
Product warranty accrual	604,388	653,473	691,832
Accrued interest	524,885	469,049
Accrued license and maintenance fees	305,977	323,901
Other	596,920	696,579
Total accrued liabilities	$ 5,038,255	$ 5,361,810