Acquisitions (Details) (USD $)	9 Months Ended
	Sep. 30, 2012
Acquisitions [Abstract]
Value of assets managed by Milestone	$ 1,300,000,000
Total purchase price of acquisitions	41,000,000
Cash paid for acquisitions	29,000,000
Contingent consideration for acquisitions	12,000,000
Identifiable intangibles created from acquisitions	25,000,000
Goodwill created from acquisitions	$ 23,000,000