Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries [Abstract]
Parent company's percentage ownership of guarantors (as a percent)	100.00%
Assets
Cash and cash equivalents	$ 109,015	$ 104,402	$ 124,281	$ 260,131
Accounts receivable, net	210,145	182,467
Restricted Cash	30,398	889
Inventories	71,255	79,742
Notes Receivable	10,298	0	10,000
Other current assets	53,782	38,945
Property and equipment, net	376,877	426,488
Goodwill	801,098	768,393	763,915
Intangible assets	84,291	86,859
Other assets	439,749	474,615
Total assets	2,186,908	2,161,911	2,151,538
Liabilities and stockholders' equity
Current installments of long-term debt	16,458	26,191
Other current liabilities	239,889	210,902
Long-term debt, excluding current installments	1,451,708	1,364,476
Other non-current liabilities	114,062	116,628
Stockholders’ equity	364,791	443,714	452,658
Total liabilities and stockholders' equity	2,186,908	2,161,911
Parent Company
Assets
Cash and cash equivalents	27,159	24,042
Notes Receivable	10,298
Other current assets	9,693	8,699
Property and equipment, net	5,727	3,522
Investment in subsidiaries	520,969	551,256
Intercompany balances	79,735	125,440
Other assets	6,479	17,002
Total assets	660,060	729,961
Liabilities and stockholders' equity
Other current liabilities	28,485	31,231
Long-term debt, excluding current installments	250,000	250,000
Other non-current liabilities	16,784	5,016
Stockholders’ equity	364,791	443,714
Total liabilities and stockholders' equity	660,060	729,961
SGI
Assets
Cash and cash equivalents	201	56
Accounts receivable, net	63,944	53,531
Inventories	25,411	23,714
Other current assets	3,809	3,409
Property and equipment, net	154,243	166,637
Investment in subsidiaries	802,425	721,909
Goodwill	253,928	273,656
Intangible assets	42,000	41,520
Other assets	74,923	82,748
Total assets	1,420,884	1,367,180
Liabilities and stockholders' equity
Current installments of long-term debt	6,280	6,280
Other current liabilities	58,473	56,050
Long-term debt, excluding current installments	1,199,247	1,104,884
Other non-current liabilities	25,560	38,772
Intercompany balances	136,402	71,603
Stockholders’ equity	(5,078)	89,591
Total liabilities and stockholders' equity	1,420,884	1,367,180
Guarantor Subsidiaries
Assets
Accounts receivable, net	29,156	41,238
Inventories	16,063	16,884
Other current assets	6,773	5,117
Property and equipment, net	32,957	36,028
Goodwill	76,741	78,618
Intangible assets	20,367	25,849
Intercompany balances	302,396	231,357
Other assets	7,507	12,265
Total assets	491,960	447,356
Liabilities and stockholders' equity
Other current liabilities	35,436	30,140
Other non-current liabilities	12,174	13,427
Stockholders’ equity	444,350	403,789
Total liabilities and stockholders' equity	491,960	447,356
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	82,834	81,482
Accounts receivable, net	117,045	87,698
Restricted Cash	30,398
Inventories	29,781	39,144
Other current assets	33,507	21,720
Property and equipment, net	183,950	220,301
Investment in subsidiaries	855,801	909,379
Goodwill	470,429	416,119
Intangible assets	21,924	19,490
Other assets	353,455	368,701
Total assets	2,179,124	2,164,034
Liabilities and stockholders' equity
Current installments of long-term debt	10,178	19,911
Other current liabilities	118,682	94,692
Long-term debt, excluding current installments	2,461	9,592
Other non-current liabilities	59,544	59,413
Intercompany balances	245,748	285,162
Stockholders’ equity	1,742,511	1,695,264
Total liabilities and stockholders' equity	2,179,124	2,164,034
Eliminating Entries
Assets
Cash and cash equivalents	(1,179)	(1,178)
Investment in subsidiaries	(2,179,195)	(2,182,544)
Intercompany balances	(382,131)	(356,797)
Other assets	(2,615)	(6,101)
Total assets	(2,565,120)	(2,546,620)
Liabilities and stockholders' equity
Other current liabilities	(1,187)	(1,211)
Intercompany balances	(382,150)	(356,765)
Stockholders’ equity	(2,181,783)	(2,188,644)
Total liabilities and stockholders' equity	$ (2,565,120)	$ (2,546,620)