Acquisitions (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Acquisition and integration costs	$ 70,000,000	$ 42,000,000	$ 20,000,000	$ 11,000,000	$ 10,000,000				$ 141,605,000	$ 9,652,000	$ 81,737,000
Acquisition costs									15,000,000
Integration costs									127,000,000
Capital Expenditures Integration Activities									115,653,000		54,097,000
Revenue	1,330,305,000	1,140,874,000	1,147,265,000	1,154,046,000	1,180,369,000	1,185,278,000	1,190,533,000	1,205,396,000	4,772,490,000	4,761,576,000	5,011,853,000
Operating income	172,543,000	197,031,000	224,342,000	226,025,000	257,569,000	206,172,000	266,156,000	250,824,000	819,941,000	980,721,000	987,168,000
Goodwill deductible for income tax purposes	75,000,000								75,000,000
Connecticut Operations [Member]
Business Acquisition [Line Items]
Acquisition purchase price	2,000,000,000								2,000,000,000
Revenue	216,000,000
Operating income	$ 38,000,000