Significant Accounting Policies (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013 Source Project Method	Mar. 31, 2012 Project	Dec. 31, 2012 Project
Accounting Policies [Abstract]
Number of product revenue sources	2
Unbilled receivables	$ 54.3		$ 62.1
Number of projects	14	13	21
Percentage of total revenues	19.00%	17.00%	20.00%
Percentage of product revenues	22.00%	20.00%	24.00%
Number of service revenue sources	3