Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009
Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries
Parent company's percentage ownership of guarantors (as a percent)	100.00%
Assets
Cash and cash equivalents	$ 86,879		$ 124,281	$ 249,570	$ 260,131
Accounts receivable, net	187,236		178,179
Inventories	79,396		68,744
Other current assets	54,774		42,461
Property and equipment, net	438,299		450,581
Investment in subsidiaries		37,000
Goodwill	766,288		763,915
Intangible assets	88,792		70,613
Other assets	494,677		452,764
Total assets	2,196,341		2,151,538
Liabilities and stockholders' equity
Current installments of long-term debt	9,391		8,431
Other current liabilities	224,881		187,567
Long-term debt, excluding current installments	1,382,393		1,388,259
Other non-current liabilities	118,899		114,623
Stockholders' equity	460,777		452,658
Total liabilities and stockholders' equity	2,196,341		2,151,538
Parent Company
Assets
Cash and cash equivalents	20,680		62,639
Other current assets	15,247		14,997
Property and equipment, net	2,998		1,730
Investment in subsidiaries	571,939		510,260
Intercompany balances	125,579		133,483
Other assets	17,009		18,457
Total assets	753,452		741,566
Liabilities and stockholders' equity
Other current liabilities	34,829		29,363
Long-term debt, excluding current installments	250,000		250,000
Other non-current liabilities	7,846		9,545
Stockholders' equity	460,777		452,658
Total liabilities and stockholders' equity	753,452		741,566
SGI
Assets
Cash and cash equivalents	106		150
Accounts receivable, net	47,902		72,830
Inventories	26,840		29,416
Other current assets	3,586		2,783
Property and equipment, net	168,613		150,130
Investment in subsidiaries	726,496		670,471
Goodwill	273,657		273,656
Intangible assets	41,686		42,170
Other assets	80,456		98,933
Total assets	1,369,342		1,340,539
Liabilities and stockholders' equity
Current installments of long-term debt	6,280		6,280
Other current liabilities	62,174		48,074
Long-term debt, excluding current installments	1,106,303		1,110,573
Other non-current liabilities	40,362		43,188
Intercompany balances	48,728		27,292
Stockholders' equity	105,495		105,132
Total liabilities and stockholders' equity	1,369,342		1,340,539
Guarantor Subsidiaries
Assets
Accounts receivable, net	46,924		45,541
Inventories	14,589		16,210
Other current assets	5,755		4,564
Property and equipment, net	36,166		43,859
Goodwill	78,618		78,843
Intangible assets	26,215		20,481
Intercompany balances	217,193		164,982
Other assets	11,858		6,046
Total assets	437,318		380,526
Liabilities and stockholders' equity
Other current liabilities	26,577		32,601
Other non-current liabilities	15,711		8,141
Stockholders' equity	395,030		339,784
Total liabilities and stockholders' equity	437,318		380,526
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	68,705		62,770
Accounts receivable, net	92,410		59,808
Inventories	37,967		23,118
Other current assets	30,186		20,117
Property and equipment, net	230,522		254,862
Investment in subsidiaries	908,216		386,690
Goodwill	414,013		411,416
Intangible assets	20,891		7,962
Other assets	391,455		335,429
Total assets	2,194,365		1,562,172
Liabilities and stockholders' equity
Current installments of long-term debt	3,111		2,151
Other current liabilities	103,914		78,817
Long-term debt, excluding current installments	26,090		27,686
Other non-current liabilities	54,980		53,749
Intercompany balances	294,045		271,186
Stockholders' equity	1,712,225		1,128,583
Total liabilities and stockholders' equity	2,194,365		1,562,172
Eliminating Entries
Assets
Cash and cash equivalents	(2,612)		(1,278)
Investment in subsidiaries	(2,206,651)		(1,567,421)
Intercompany balances	(342,772)		(298,465)
Other assets	(6,101)		(6,101)
Total assets	(2,558,136)		(1,873,265)
Liabilities and stockholders' equity
Other current liabilities	(2,613)		(1,288)
Intercompany balances	(342,773)		(298,478)
Stockholders' equity	(2,212,750)		(1,573,499)
Total liabilities and stockholders' equity	$ (2,558,136)		$ (1,873,265)