Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended		9 Months Ended	12 Months Ended	3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Perkins	Dec. 31, 2012 Perkins	Mar. 31, 2013 INTECH
Significant unobservable inputs
Maturity period of short-term securities valued at amortized costs	60 days
Transfers from Level 2 to Level 1	$ 13.4	$ 4.9
Discount rate					13.00%
Terminal multiple					7.50
Period of revenues			12 months
Revenue multiples			3.39	3.43