Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of amounts capitalized	$ 109,112	$ 39,539	$ 34,034
Cash paid for income taxes	42,261	22,320	25,435
Details of business acquisitions:
Fair value of assets	4,364,872	8,650	515,767
Fair value of liabilities	(695,243)	(6,902)	(228,417)
Common stock issued	(2,361,466)
Cash paid	1,308,163	1,748	287,350
Less cash acquired	(217,002)		(11,273)
Net cash paid for acquisitions	1,091,161	1,748	276,077
Details of proceeds from sale of businesses:
Book value of assets	198,369	13,791	4,236
Book value of liabilities	(8,626)		81
Book value of liabilities	8,626		(81)
Receivable due from sale			(150)
Gain on sale of business	(6,649)	8,558	1,083
Proceeds from sale of businesses	183,094	22,349	5,250
Non-cash investing activity:
Capital expenditures included in accounts payable	61,035	23,053
Additional consideration payable on acquisitions	9,890
Non-cash financing activity:
Share settlement for employee tax liability			$ 3,093