Consolidated Financial Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidated Financial Statements
Ownership interest in subsidiaries (as a percent)			100.00%
External commissions	$ 6.3	$ 4.5	$ 10.9	$ 7.6
Percentage of external commissions to housing revenues	2.20%	2.20%	2.20%	2.10%

Primarily represents commissions incurred in the period based upon the sale by commissioned employees or third parties of the entity's goods or services, and fees for sales assistance or product enhancements performed by third parties (such as a distributor or value added reseller).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.4)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Name:	us-gaap_SalesCommissionsAndFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration