Consolidated Statement of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues	$ 2,994,012	$ 2,550,466	$ 2,404,430
Costs and expenses	(2,318,199)	(2,001,419)	(1,881,658)
Gross profits	675,813	549,047	522,772
General and administrative expenses	(184,877)	(155,128)	(121,891)
Gains (losses) on divestitures and impairment charges, net	116,613	(6,263)	(1,511)
Operating income	607,549	387,656	399,370
Interest expense	(177,571)	(142,360)	(135,068)
(Losses) gains on early extinguishment of debt, net	(29,158)	468	(22,706)
Other income (expense), net	1,780	(558)	3,687
Income from continuing operations before income taxes	402,600	245,206	245,283
Provision for income taxes	(225,980)	(93,024)	(90,111)
Income from continuing operations	176,620	152,182	155,172
Income from discontinued operations, net of tax	2,186	406	262
Net income	178,806	152,588	155,434
Net income attributable to noncontrolling interests	(6,337)	(5,256)	(1,589)
Net income attributable to common stockholders	$ 172,469	$ 147,332	$ 153,845
Basic earnings per share:
Net income attributable to common stockholders, basic	$ 0.82		$ 0.71
Basic weighted average number of shares	210,741	211,811	215,712
Diluted earnings per share:
Net income attributable to common stockholders, diluted	$ 0.81		$ 0.70
Diluted weighted average number of shares	214,200	216,014	219,066
Dividends declared per share	$ 0.34	$ 0.27	$ 0.23