Quarterly Financial Data Quarterly Financial Data Level 4 (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	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
Quarterly Financial Data (Unaudited) [Abstract]
Revenues	$ 783,443		$ 718,314		$ 746,746		$ 745,509		$ 667,228		$ 608,589		$ 624,231		$ 650,418		$ 2,994,012	$ 2,550,466	$ 2,404,430
Costs and expenses	(578,032)		(570,016)		(590,882)		(579,269)		(519,296)		(492,784)		(498,248)		(491,092)		(2,318,199)	(2,001,419)	(1,881,658)
Gross profits	205,411		148,298		155,864		166,240		147,932		115,805		125,983		159,326		675,813	549,047	522,772
Operating income	220,280		135,120		144,731		107,418		88,117		83,046		89,059		127,434		607,549	387,656	399,370
Income from continuing operations before income taxes	177,591	[1]	91,735	[1]	69,316	[1]	63,958	[1]	49,801	[1]	45,633	[1]	56,092	[1]	93,680	[1]	402,600	245,206	245,283
Provision for income taxes	(90,982)		(74,934)		(37,357)		(22,707)		(17,729)	[2]	(18,407)	[2]	(21,598)	[2]	(35,290)	[2]	225,980	93,024	90,111
Net income	87,949		17,685		31,781		41,391		32,037		27,394		34,435		58,722		178,806	152,588	155,434
Net income attributable to noncontrolling interests	(155)		(34)		(5,859)		(289)		(2,719)		(615)		(820)		(1,102)		(6,337)	(5,256)	(1,589)
Net income attributable to common stockholders	$ 87,794		$ 17,651		$ 25,922		$ 41,102		$ 29,318	[2]	$ 26,779	[2]	$ 33,615	[2]	$ 57,620	[2]	$ 172,469	$ 147,332	$ 153,845
Basic — EPS	$ 0.42	[3]	$ 0.08	[3]	$ 0.12	[3]	$ 0.19	[3]	$ 0.14	[3]	$ 0.13	[3]	$ 0.16	[3]	$ 0.27	[3]	$ 0.82		$ 0.71
Earnings per share, diluted	$ 0.42	[3]	$ 0.08	[3]	$ 0.12	[3]	$ 0.19	[3]	$ 0.14	[3]	$ 0.12	[3]	$ 0.16	[3]	$ 0.27	[3]	$ 0.81		$ 0.70

[1] Includes (Losses) gains on divestitures and impairment charges, net, as described in Note 20.

[2] See Note 2 for details related to the revision which was recorded for the quarter ended December 31, 2013. The revision reduced the provision for income taxes and increased net income attributable to common stockholders by $3.5 million and increased basic and diluted EPS by $0.02.

[3] Net income per share is computed independently for each of the quarters presented. Therefore, the sum of the quarters’ net income per share may not equal the total computed for the year.