Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended						12 Months Ended
	Mar. 31, 2013 Y	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013 Y	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2008 Impella	May 31, 2005 Impella	Mar. 31, 2013 Federal	Mar. 31, 2013 State	Mar. 31, 2013 GERMANY (WEST)
Income Taxes [Line Items]
Net operating loss carry forwards													$ 19,400,000	$ 188,900,000	$ 105,900,000
Net operating loss carry forwards expiration period									Fiscal 2014 through fiscal 2033
Net operating loss carry forwards expired															21,200,000
Research and development credit carry forwards														11,600,000	5,500,000
Net operating loss carry forwards that could not be utilized												1,300,000
NOL carryforwards																53,800,000
Increase(decrease) in valuation allowance									400,000	2,400,000
Net deferred tax liability	5,554,000				4,799,000				5,554,000	4,799,000
Amortization period of deferred tax liability (years)	15								15
Income tax provision	$ 398,000	$ 559,000	$ 455,000	$ 436,000	$ 361,000	$ 366,000	$ 225,000	$ 96,000	$ 1,848,000	$ 1,048,000	$ 892,000					$ 0.000