Consolidated Statement of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues	$ 629,421		$ 581,182		$ 597,372		$ 602,506		$ 586,568		$ 572,999		$ 576,774		$ 579,699		$ 2,410,481	$ 2,316,040	$ 2,190,552
Costs and expenses	(481,221)		(459,911)		(469,183)		(474,939)		(456,551)		(465,949)		(461,751)		(453,253)		(1,885,254)	(1,837,504)	(1,741,329)
Gross profits	148,200		121,271		128,189		127,567		130,017		107,050		115,023		126,446		525,227	478,536	449,223
General and administrative expenses																	(123,905)	(103,860)	(103,689)
(Losses) gains on divestitures and impairment charges, net																	(1,533)	(10,977)	8,512
Operating income	103,806		95,176		99,689		101,118		107,825		78,186		80,495		97,193		399,789	363,699	354,046
Interest expense																	(135,068)	(133,782)	(128,196)
Losses on early extinguishment of debt, net																	(22,706)	(3,509)	(9,400)
Other income (expense), net																	3,668	(772)	3,009
Income from continuing operations before income taxes	46,749	[1]	63,925	[1]	63,574	[1]	71,435	[1]	72,773	[1]	44,042	[1]	44,827	[1]	63,994	[1]	245,683	225,636	219,459
Provision for income taxes	20,365		22,128		25,935		23,120		28,223		9,027		18,089		24,065		(91,548)	(79,404)	(92,458)
Net income	26,384		41,797		37,639		48,315		44,550		35,015		26,738		39,929		154,135	146,232	127,001
Net income attributable to noncontrolling interests	(1)		(735)		(563)		(290)		0		481		(645)		(1,165)		(1,589)	(1,329)	(584)
Net income attributable to common stockholders	$ 26,383		$ 41,062		$ 37,076		$ 48,025		$ 44,550		$ 35,496		$ 26,093		$ 38,764		$ 152,546	$ 144,903	$ 126,417
Basic earnings per share:
Net income attributable to common stockholders, basic	$ 0.12	[2]	$ 0.19	[2]	$ 0.17	[2]	$ 0.22	[2]	$ 0.20	[2]	$ 0.15	[2]	$ 0.11	[2]	$ 0.16	[2]	$ 0.71	$ 0.62	$ 0.51
Basic weighted average number of shares																	215,712	234,242	248,871
Diluted earnings per share:
Net income attributable to common stockholders, diluted	$ 0.12	[2]	$ 0.19	[2]	$ 0.17	[2]	$ 0.22	[2]	$ 0.20	[2]	$ 0.15	[2]	$ 0.11	[2]	$ 0.16	[2]	$ 0.70	$ 0.61	$ 0.50
Diluted weighted average number of shares																	219,066	236,669	250,602
Dividends declared per share	$ 0.06																$ 0	$ 0	$ 0

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

[2] 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.