Debt, Commitments And Contingencies (Narrative) (Details) (USD $)									9 Months Ended											0 Months Ended
	Sep. 30, 2011	Jul. 08, 2011	May 06, 2011	Dec. 31, 2010	Sep. 30, 2011 Floating Per Annum Rate [Member] Maximum [Member]	Sep. 30, 2011 Floating Per Annum Rate [Member] Minimum [Member]	Sep. 30, 2011 Reserve-Adjusted Fixed Per Annum Rate [Member] Maximum [Member]	Sep. 30, 2011 Reserve-Adjusted Fixed Per Annum Rate [Member] Minimum [Member]	Sep. 30, 2011 Maximum [Member]	Sep. 30, 2011 Minimum [Member]	Sep. 30, 2011 2011 Credit Facility [Member]	May 06, 2011 2011 Credit Facility [Member]	Sep. 30, 2011 Term Loan [Member]	May 06, 2011 Term Loan [Member]	Sep. 30, 2011 Revolving Credit Facility [Member]	May 06, 2011 Revolving Credit Facility [Member]	Dec. 31, 2010 Revolving Credit Facility [Member]	Sep. 30, 2011 Promissory Notes And Other [Member]	Dec. 31, 2010 Promissory Notes And Other [Member]	Jul. 14, 2011 2011 Uncommitted Facility [Member]	Sep. 30, 2011 2011 Uncommitted Facility [Member]
Debt Commitments And Contingencies [Line Items]
Unsecured revolving credit agreement, available borrowing capacity												$ 1,100,000,000
Credit facility maximum borrowing amount																700,000,000
Term loan credit facility maximum borrowing amount														400,000,000
Unsecured revolving credit facility, additional borrowing capacity												300,000,000
Uncommitted revolving loan facility																				50,000,000
Total debt	637,253,000			153,153,000							200,000,000		390,000,000		245,000,000		151,000,000	2,253,000	2,153,000		45,000,000
Non-current portion of long-term debt	570,380,000			151,160,000									370,000,000		200,000,000
Credit facility initial borrowing amount			151,000,000
Unsecured revolving credit facility, initiation date											May 6, 2011
Unsecured revolving credit facility, expiration date											May 6, 2016
Credit facility term period, years												5
Term loan credit facility term period, years												5
Credit facility commitment fee, percentage									0.40%	0.20%
Amortization of credit facility, percentage, year one											5.00%
Amortization of credit facility, percentage, year two											5.00%
Amortization of credit facility, percentage, year three											10.00%
Amortization of credit facility, percentage, year four											10.00%
Amortization of credit facility, percentage, year five											70.00%
Credit facility interest rate in addition to specific base rates					1.25%	0.25%	2.25%	1.25%													1.00%
Maximum leverage and minimum interest coverage ratio											3.5
Debt instrument, face amount																		2,300,000	2,200,000
Outstanding notes payable																		1,800,000
Interest rate on notes																		6.00%
Acquisition-related holdbacks as non-current liabilities	5,900,000	3,093,000
Fair value of the contingent consideration	5,100,000
Additional potential earn-out cash payments	11,200,000
Unconditional purchase obligations	68,200,000
Line of Credit Facility, Maximum Borrowing Capacity												$ 1,100,000,000