Subsidiary Guarantors (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 36,868	$ 29,997	$ 61,076	$ 50,134
Accounts receivable, net	251,191	241,873
Refundable income taxes	926
Deferred income taxes	26,820	19,811
Non-trade receivables	4,503	6,852
Prepaid expenses and other current assets	17,916	19,578
Total current assets	338,224	318,111
Property and equipment, net	101,621	101,021
Goodwill	308,927	308,350
Other intangible assets, net	329,680	333,613
Other assets	26,068	25,182
Total assets	1,104,520	1,086,277	1,067,129
Current liabilities:
Trade accounts payable	37,503	34,089
Accrued expenses	133,168	120,803
Current portion of long-term debt	11,185	14,291
Obligations under capital leases	6,515	6,516
Accrued income taxes	3,218
Total current liabilities	191,589	175,699
Long-term liabilities	43,631	39,143
Long-term debt	450,036	345,506
Obligations under capital leases	14,485	13,724
Deferred income taxes	119,189	116,084
Total liabilities	818,930	690,156
Common stock
Additional paid-in capital	248,036	247,053
Retained earnings	38,132	149,617
Accumulated other comprehensive (loss) income	(578)	(549)
Total shareholder's equity	285,590	396,121
Total liabilities and shareholder's equity	1,104,520	1,086,277
Parent Company [Member]
Current assets:
Cash and cash equivalents	35,450	26,335	57,765	42,633
Accounts receivable, net	31,100	25,953
Refundable income taxes	926
Deferred income taxes	26,820	19,811
Non-trade receivables	3,409	4,592
Prepaid expenses and other current assets	8,386	10,793
Total current assets	106,091	87,484
Property and equipment, net	49,879	50,854
Goodwill	303,870	303,270
Other intangible assets, net	295,177	297,535
Investment in subsidiaries	1,010,952	990,793
Other assets	19,981	18,746
Total assets	1,785,950	1,748,682
Current liabilities:
Trade accounts payable	22,739	17,851
Accrued expenses	73,629	61,175
Current portion of long-term debt	10,000	13,125
Accrued income taxes	3,218
Total current liabilities	109,586	92,151
Intercompany	779,684	761,430
Long-term liabilities	42,976	38,508
Long-term debt	448,925	344,388
Deferred income taxes	119,189	116,084
Total liabilities	1,500,360	1,352,561
Additional paid-in capital	248,036	247,053
Retained earnings	38,132	149,617
Accumulated other comprehensive (loss) income	(578)	(549)
Total shareholder's equity	285,590	396,121
Total liabilities and shareholder's equity	1,785,950	1,748,682
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	505	2,860	2,693	4,795
Accounts receivable, net	220,022	215,864
Non-trade receivables	1,071	2,237
Prepaid expenses and other current assets	9,516	8,765
Total current assets	231,114	229,726
Property and equipment, net	51,712	50,160
Goodwill	27	27
Other intangible assets, net	34,503	36,078
Intercompany	713,512	695,097
Investment in subsidiaries	37,913	37,913
Other assets	6,087	6,436
Total assets	1,074,868	1,055,437
Current liabilities:
Trade accounts payable	14,741	16,210
Accrued expenses	58,943	58,950
Current portion of long-term debt	1,185	1,166
Obligations under capital leases	6,515	6,516
Total current liabilities	81,384	82,842
Long-term liabilities	655	635
Long-term debt	1,111	1,118
Obligations under capital leases	14,485	13,724
Total liabilities	97,635	98,319
Additional paid-in capital	478,422	478,422
Retained earnings	498,829	478,714
Accumulated other comprehensive (loss) income	(18)	(18)
Total shareholder's equity	977,233	957,118
Total liabilities and shareholder's equity	1,074,868	1,055,437
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	913	802	618	2,706
Accounts receivable, net	69	56
Non-trade receivables	23	23
Prepaid expenses and other current assets	14	20
Total current assets	1,019	901
Property and equipment, net	30	7
Goodwill	5,030	5,053
Intercompany	68,266	68,427
Total assets	74,345	74,388
Current liabilities:
Trade accounts payable	23	28
Accrued expenses	596	678
Total current liabilities	619	706
Total liabilities	619	706
Additional paid-in capital	122,023	121,814
Retained earnings	(47,134)	(47,178)
Accumulated other comprehensive (loss) income	(1,163)	(954)
Total shareholder's equity	73,726	73,682
Total liabilities and shareholder's equity	74,345	74,388
Consolidation, Eliminations [Member]
Current assets:
Intercompany	(781,778)	(763,524)
Investment in subsidiaries	(1,048,865)	(1,028,706)
Total assets	(1,830,643)	(1,792,230)
Current liabilities:
Intercompany	(779,684)	(761,430)
Total liabilities	(779,684)	(761,430)
Additional paid-in capital	(600,445)	(600,236)
Retained earnings	(451,695)	(431,536)
Accumulated other comprehensive (loss) income	1,181	972
Total shareholder's equity	(1,050,959)	(1,030,800)
Total liabilities and shareholder's equity	$ (1,830,643)	$ (1,792,230)