Noncontrolling Interest (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 item	Sep. 30, 2012
Redeemable Noncontrolling Interest
Number of firms in which entity holds majority ownership interest	5
Fair value of noncontrolling owners equity interests	$ 39,840
Redeemable noncontrolling interest
Balance, beginning of period	41,112
Net income	1,657	1,024
Balance, end of period	39,840
Redeemable Noncontrolling Interest
Redeemable Noncontrolling Interest
Number of firms in which entity holds majority ownership interest	5
Fair value of noncontrolling owners equity interests	39,840	41,386
Redeemable noncontrolling interest
Balance, beginning of period	41,112	44,643
Net income	1,657	1,024
Distributions to redeemable noncontrolling interest	(1,285)	(1,261)
Additions and redemptions, net	(1,625)	(1,987)
Adjustments to fair value	(19)	(1,033)
Balance, end of period	$ 39,840	$ 41,386