Revenue And Credit Concentration (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Schedule of Revenue and Credit Concentrations [Line Items]
Revenue concentration risk	10.00%
Accounts Receivable Rank One Customer [Member]
Schedule of Revenue and Credit Concentrations [Line Items]
Percentage of accounts receivable balances of largest customers	43.00%	47.00%
Unbilled accounts receivable related to net incremental Aldurazyme product transfers to Genzyme	$ 28.4	$ 23.1
Accounts Receivable Rank Two Customer [Member]
Schedule of Revenue and Credit Concentrations [Line Items]
Percentage of accounts receivable balances of largest customers	13.00%	17.00%
Accounts Receivable Rank Three Customer [Member]
Schedule of Revenue and Credit Concentrations [Line Items]
Percentage of accounts receivable balances of largest customers	12.00%