Financial Information Related to Guarantor Subsidaries (Details 1) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Financial Information Related to Subsidiaries [Abstract]
Revenues	$ 510,806	$ 424,856	$ 924,787	$ 789,367
Costs and expenses:
Cost of services (exclusive of items shown separately below)	271,370	229,916	505,215	428,968
Depreciation, depletion, amortization and accretion	63,314	54,299	122,677	105,347
General and administrative expenses	95,881	92,529	182,760	163,253
Gain on sale of businesses	5,884		8,558
Income (loss) from operation	86,125	48,112	122,693	91,799
Other income (expense):
Interest income (expense), net	(16,453)	(12,680)	(28,825)	(26,718)
Earnings (losses) from equity-method investments, net	5,499	2,170	5,526	6,155
Income (loss) before income taxes	75,171	37,602	99,394	71,236
Income taxes	27,062	13,537	35,782	25,645
Net income (loss)	48,109	24,065	63,612	45,591
Parent [Member]
Costs and expenses:
General and administrative expenses	205	79	530	168
Income (loss) from operation	(205)	(79)	(530)	(168)
Other income (expense):
Income (loss) before income taxes	(205)	(79)	(530)	(168)
Income taxes	24,220	11,656	31,819	20,035
Net income (loss)	(24,425)	(11,735)	(32,349)	(20,203)
Issuer [Member]
Costs and expenses:
Depreciation, depletion, amortization and accretion	129	128	257	257
General and administrative expenses	20,329	33,446	39,247	50,643
Income (loss) from operation	(20,458)	(33,547)	(39,504)	(50,900)
Other income (expense):
Interest income (expense), net	(17,499)	(13,311)	(30,060)	(27,333)
Intercompany interest income/(expense)	6,605	3,526	12,811	5,673
Earnings (losses) from equity-method investments, net	5,278	1,667	4,400	2,500
Income (loss) before income taxes	(26,074)	(41,692)	(52,353)	(70,060)
Net income (loss)	(26,074)	(41,692)	(52,353)	(70,060)
Guarantor Subsidiaries [Member]
Financial Information Related to Subsidiaries [Abstract]
Revenues	434,235	361,612	785,875	670,101
Costs and expenses:
Cost of services (exclusive of items shown separately below)	221,684	193,793	415,770	364,239
Depreciation, depletion, amortization and accretion	51,741	44,446	100,432	87,165
General and administrative expenses	55,785	47,786	107,954	91,247
Gain on sale of businesses	5,884		8,558
Income (loss) from operation	110,909	75,587	170,277	127,450
Other income (expense):
Interest income (expense), net	1,212	1,259	2,288	1,957
Income (loss) before income taxes	112,121	76,486	172,565	129,407
Net income (loss)	112,121	76,846	172,565	129,407
Non-Guarantor Subsidiaries [Member]
Financial Information Related to Subsidiaries [Abstract]
Revenues	97,714	86,205	175,832	153,972
Costs and expenses:
Cost of services (exclusive of items shown separately below)	70,766	59,084	126,238	99,435
Depreciation, depletion, amortization and accretion	11,444	9,725	21,988	17,925
General and administrative expenses	19,625	11,218	35,156	21,195
Income (loss) from operation	(4,121)	6,178	(7,550)	15,417
Other income (expense):
Interest income (expense), net	(166)	(628)	(1,053)	(1,342)
Intercompany interest income/(expense)	(6,605)	(3,526)	(12,811)	(5,673)
Earnings (losses) from equity-method investments, net	221	503	1,126	3,655
Income (loss) before income taxes	(10,671)	2,527	(20,288)	12,057
Income taxes	2,842	1,881	3,963	5,610
Net income (loss)	(13,513)	646	(24,251)	6,447
Consolidation, Eliminations [Member]
Financial Information Related to Subsidiaries [Abstract]
Revenues	(21,143)	(22,961)	(36,920)	(34,706)
Costs and expenses:
Cost of services (exclusive of items shown separately below)	(21,080)	(22,961)	(36,793)	(34,706)
General and administrative expenses	$ (63)		$ (127)