Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Assets
Cash and cash equivalents	$ 127,256	$ 124,281	$ 151,453	$ 260,131
Accounts receivable, net	166,771	178,179
Inventories	69,229	68,744
Other current assets	52,623	42,461
Property and equipment, net	436,684	450,581
Investment in subsidiaries	37,000
Goodwill	780,927	763,915
Intangible assets	78,659	70,613
Other assets	502,542	452,764
Total assets	2,214,691	2,151,538
Liabilities and stockholders' equity
Current installments of long-term debt	9,479	8,431
Other current liabilities	190,132	187,567
Long-term debt, excluding current installments	1,381,335	1,388,259
Other non-current liabilities	124,720	114,623
Stockholders' equity	509,025	452,658
Total liabilities and stockholders' equity	2,214,691	2,151,538
Parent Company
Assets
Cash and cash equivalents	30,903	62,639	98,097	147,220
Other current assets	14,382	14,997
Property and equipment, net	2,617	1,730
Investment in subsidiaries	606,561	510,260
Intercompany balances	136,895	133,483
Other assets	17,836	18,457
Total assets	809,194	741,566
Liabilities and stockholders' equity
Other current liabilities	39,800	29,363
Long-term debt, excluding current installments	250,000	250,000
Other non-current liabilities	10,369	9,545
Stockholders' equity	509,025	452,658
Total liabilities and stockholders' equity	809,194	741,566
SGI
Assets
Cash and cash equivalents	137	150	623	137
Accounts receivable, net	51,295	72,830
Inventories	26,375	29,416
Other current assets	3,337	2,783
Property and equipment, net	167,434	150,130
Investment in subsidiaries	706,241	670,471
Goodwill	273,656	273,656
Intangible assets	41,255	42,170
Other assets	77,161	98,933
Total assets	1,347,291	1,340,539
Liabilities and stockholders' equity
Current installments of long-term debt	6,280	6,280
Other current liabilities	46,479	48,074
Long-term debt, excluding current installments	1,105,494	1,110,573
Other non-current liabilities	40,287	43,188
Intercompany balances	37,668	27,292
Stockholders' equity	111,083	105,132
Total liabilities and stockholders' equity	1,347,291	1,340,539
Guarantor Subsidiaries
Assets
Accounts receivable, net	41,924	45,541
Inventories	14,388	16,210
Other current assets	6,466	4,564
Property and equipment, net	37,003	43,859
Goodwill	78,618	78,843
Intangible assets	28,838	20,481
Intercompany balances	202,139	164,982
Other assets	10,892	6,046
Total assets	420,268	380,526
Liabilities and stockholders' equity
Other current liabilities	29,428	32,601
Other non-current liabilities	15,751	8,141
Stockholders' equity	375,089	339,784
Total liabilities and stockholders' equity	420,268	380,526
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	103,394	62,770	59,337	113,053
Accounts receivable, net	73,552	59,808
Inventories	28,466	23,118
Other current assets	28,438	20,117
Property and equipment, net	229,630	254,862
Investment in subsidiaries	856,910	386,690
Goodwill	428,653	411,416
Intangible assets	8,166	7,962
Other assets	402,754	335,429
Total assets	2,159,963	1,562,172
Liabilities and stockholders' equity
Current installments of long-term debt	3,199	2,151
Other current liabilities	81,604	78,817
Long-term debt, excluding current installments	25,841	27,686
Other non-current liabilities	58,313	53,749
Intercompany balances	301,367	271,186
Stockholders' equity	1,689,639	1,128,583
Total liabilities and stockholders' equity	2,159,963	1,562,172
Eliminating Entries
Assets
Cash and cash equivalents	(7,178)	(1,278)
Investment in subsidiaries	(2,169,712)	(1,567,421)
Intercompany balances	(339,034)	(298,465)
Other assets	(6,101)	(6,101)
Total assets	(2,522,025)	(1,873,265)
Liabilities and stockholders' equity
Other current liabilities	(7,179)	(1,288)
Intercompany balances	(339,035)	(298,478)
Stockholders' equity	(2,175,811)	(1,573,499)
Total liabilities and stockholders' equity	$ 2,522,025	$ (1,873,265)