Restructuring Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Restructuring Costs [Abstract]
Number of division offices to be consolidated	2
Number of regional offices created	1
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs	$ 5.8
Restructuring costs incurred to date	2.7
Increase (Decrease) in Restructuring Liability [Roll Forward]
Balance at December 31, 2011	0
Costs incurred and charged to expense	2.7
Costs paid or otherwise settled	(2.4)
Balance at March 31, 2012	0.3
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs	1.7
Restructuring costs incurred to date	1.1
Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs	3.6
Termination of Lease [Member]
Restructuring Cost and Reserve [Line Items]
Estimated restructuring costs	$ 0.5