Formation Of Joint Venture (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended			18 Months Ended	0 Months Ended	12 Months Ended
	Oct. 01, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011	Jul. 04, 2010 Apex [Member]	Dec. 31, 2011 Apex [Member]	Dec. 31, 2010 Apex [Member]	Dec. 31, 2009 Apex [Member]
Sales of contributed business			$ 315,600,000	$ 607,900,000					$ 1,200,000,000
Ownership in limited liability company					50.00%	50.00%
Term debt finance						45,000,000
Receivables from the formation of joint venture						45,000,000
After-tax gain on contribution to joint venture	232,200,000
Gain from joint venture per diluted share	$ 0.34
Proceeds from contribution of businesses to joint venture		14,770,000	56,542,000			45,000,000
Earnings from unconsolidated joint venture		$ 66,780,000	$ 22,768,000				$ 67,000,000	$ 23,000,000