Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
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	$ 73,461	$ 109,015	$ 135,954	$ 104,402
Restricted cash	50	30,398
Accounts receivable, net	200,352	209,870
Inventories	79,256	71,255
Notes receivable	0	10,298
Other current assets	52,022	53,782
Property and equipment, net	375,069	376,877
Investment in subsidiaries	0	0
Goodwill	800,372	801,373
Intangible assets	92,110	84,291
Intercompany balances	0	0
Other assets	483,536	439,749
Total assets	2,156,228	2,186,908
Liabilities and stockholders' equity
Current installments of long-term debt	11,085	16,458
Other current liabilities	209,489	239,889
Long-term debt, excluding current installments	1,448,051	1,451,708
Other non-current liabilities	132,964	114,062
Intercompany balances	0	0
Stockholders’ equity	354,639	364,791
Total liabilities and stockholders' equity	2,156,228	2,186,908
Parent Company
Assets
Cash and cash equivalents	17,023	27,159
Restricted cash	0	0
Accounts receivable, net	0	0
Inventories	0	0
Notes receivable	0	10,298
Other current assets	9,226	9,693
Property and equipment, net	7,797	5,727
Investment in subsidiaries	566,882	520,969
Goodwill	0	0
Intangible assets	0	0
Intercompany balances	34,169	79,735
Other assets	9,336	6,479
Total assets	644,433	660,060
Liabilities and stockholders' equity
Current installments of long-term debt	0	0
Other current liabilities	23,571	28,485
Long-term debt, excluding current installments	250,000	250,000
Other non-current liabilities	16,223	16,784
Intercompany balances	0	0
Stockholders’ equity	354,639	364,791
Total liabilities and stockholders' equity	644,433	660,060
SGI
Assets
Cash and cash equivalents	102	201
Restricted cash	0	0
Accounts receivable, net	64,127	63,944
Inventories	30,996	25,411
Notes receivable	0	0
Other current assets	4,280	3,809
Property and equipment, net	140,790	154,243
Investment in subsidiaries	813,520	802,425
Goodwill	253,929	253,928
Intangible assets	41,053	42,000
Intercompany balances	0	0
Other assets	94,686	74,923
Total assets	1,443,483	1,420,884
Liabilities and stockholders' equity
Current installments of long-term debt	6,280	6,280
Other current liabilities	57,783	58,473
Long-term debt, excluding current installments	1,194,970	1,199,247
Other non-current liabilities	28,878	25,560
Intercompany balances	167,078	136,402
Stockholders’ equity	(11,506)	(5,078)
Total liabilities and stockholders' equity	1,443,483	1,420,884
Guarantor Subsidiaries
Assets
Cash and cash equivalents	0	0
Restricted cash	0	0
Accounts receivable, net	33,212	29,156
Inventories	15,899	16,063
Notes receivable		0
Other current assets	7,455	6,773
Property and equipment, net	41,568	32,957
Investment in subsidiaries	0	0
Goodwill	76,741	76,741
Intangible assets	33,440	20,367
Intercompany balances	340,481	302,396
Other assets	7,119	7,507
Total assets	555,915	491,960
Liabilities and stockholders' equity
Current installments of long-term debt	0	0
Other current liabilities	38,059	35,436
Long-term debt, excluding current installments	0	0
Other non-current liabilities	28,653	12,174
Intercompany balances	0	0
Stockholders’ equity	489,203	444,350
Total liabilities and stockholders' equity	555,915	491,960
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	61,990	82,834
Restricted cash	50	30,398
Accounts receivable, net	103,013	116,770
Inventories	32,361	29,781
Notes receivable		0
Other current assets	31,061	33,507
Property and equipment, net	184,914	183,950
Investment in subsidiaries	857,958	855,801
Goodwill	469,702	470,704
Intangible assets	17,617	21,924
Intercompany balances	0	0
Other assets	375,011	353,455
Total assets	2,133,677	2,179,124
Liabilities and stockholders' equity
Current installments of long-term debt	4,805	10,178
Other current liabilities	95,738	118,682
Long-term debt, excluding current installments	3,081	2,461
Other non-current liabilities	59,210	59,544
Intercompany balances	207,590	245,748
Stockholders’ equity	1,763,253	1,742,511
Total liabilities and stockholders' equity	2,133,677	2,179,124
Eliminating Entries
Assets
Cash and cash equivalents	(5,654)	(1,179)
Restricted cash	0	0
Accounts receivable, net	0	0
Inventories	0	0
Notes receivable	0	0
Other current assets	0	0
Property and equipment, net	0	0
Investment in subsidiaries	(2,238,360)	(2,179,195)
Goodwill	0	0
Intangible assets	0	0
Intercompany balances	(374,650)	(382,131)
Other assets	(2,616)	(2,615)
Total assets	(2,621,280)	(2,565,120)
Liabilities and stockholders' equity
Current installments of long-term debt	0	0
Other current liabilities	(5,662)	(1,187)
Long-term debt, excluding current installments	0	0
Other non-current liabilities	0	0
Intercompany balances	(374,668)	(382,150)
Stockholders’ equity	(2,240,950)	(2,181,783)
Total liabilities and stockholders' equity	$ (2,621,280)	$ (2,565,120)