Independent Investigation of the Audit Committee and Related Restatements (Restated Condensed Unaudited Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014	Sep. 30, 2014	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 49,125	$ 33,589	$ 12,142	$ 45,730	$ 94,855	$ 115,549		$ 141,216		$ 107,416
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	41,747	36,755	33,494	70,249	111,996	154,452		140,926		91,958
Non-cash interest expense			2,362	4,642	6,052	7,355		10,717		8,595
Non-cash stock-based compensation expense			3,260	7,480	11,584	15,950		12,944		4,433
Excess tax benefit from stock-based compensation			(3,246)	(3,386)	(3,494)	(3,728)	[1]	(4,315)	[1]	(759)	[1]
Provision for deferred income taxes			3,281	11,160	4,294	13,756		6,533		5,127
Other non-cash items			623	438	1,136	5,955		8,009		9,305
(Gains) losses on sales of assets, including impairment charges on discontinued operations			(1,622)	(2,593)	(4,068)	(6,434)		(1,492)		11,714
Changes in assets and liabilities, net of acquisitions:
Accounts receivable			(33,073)	(12,848)	(126,950)	163,773		(204,330)		(177,313)
Inventories			(13,313)	(37,140)	(27,553)	(12,621)		13,481		15,448
Other assets, current and long-term portion			6,608	3,273	5,202	(14,221)		6,248		(6,773)
Accounts payable and accrued expenses			(14,540)	(8,816)	15,419	(87,494)		72,514		76,285
Billings in excess of costs and earnings			(12,247)	(13,095)	2,896	(34,320)		(8,227)		15,651
Book overdrafts			1,266	(1,355)	(10,399)	9,911		6,363		116
Other liabilities, current and long-term portion			(5,389)	(8,420)	49	(4,872)		(185)		11,305
Net cash provided by operating activities			(20,394)	55,319	81,019	323,011		200,402		172,508
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired			(23,831)	(162,901)	(162,901)	(345,543)		(148,567)		(119,459)
Capital expenditures			(35,554)	(67,566)	(90,962)	(109,254)		(126,288)		(79,686)
Proceeds from sale of property and equipment			3,373	8,752	12,204	16,655		15,858		7,385
Proceeds from disposal of business, net of cash divested					0	0		(2,997)		97,728
(Payments for) proceeds from other investments			(1,098)	573	(1,046)	(1,120)		(16,173)		(284)
Net cash used in investing activities			(57,110)	(221,142)	(242,705)	(439,262)		(263,211)		(94,316)
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities			233,872	815,840	1,319,623	2,385,971		1,149,040		959,183
Repayments of credit facilities			(157,349)	(463,713)	(955,151)	(1,939,612)		(1,249,601)		(885,183)
Repayment of senior notes, including convertible notes				(105,325)	(105,325)	(202,325)		(150,000)		0
Repayments of other borrowings			(2,830)	(7,220)	(15,827)	(15,700)		(27,705)		(21,455)
Payments of capital lease obligations			(10,956)	(23,023)	(38,358)	(51,587)		(43,040)		(21,060)
Payments of tax withholdings and proceeds from stock-based awards, net			(1,451)	(578)	318	1,113		8,355		5,013
Excess tax benefit from stock-based compensation			3,246	3,386	3,494	3,728		4,315		759
Payments of acquisition-related contingent consideration				(58,902)	(60,341)	(60,341)		(18,683)		(33,936)
Payments of financing costs			(218)	(1,298)	(1,455)	(2,572)		(13,688)		(117)
Net cash provided by (used in) financing activities			64,314	159,167	146,978	118,675		58,993		(71,796)
Effect of currency translation on cash			(476)	(347)	(1,152)	(1,292)		(24)		91
Net increase (decrease) in cash and cash equivalents			(13,666)	(7,003)	(15,860)	1,132		(3,840)		6,487
Cash and cash equivalents - beginning of period	15,924	9,261	22,927	22,927	22,927	22,927		26,767		20,280
Cash and cash equivalents - end of period	7,067	15,924	9,261	15,924	7,067	24,059		22,927		26,767
Supplemental cash flow information:
Interest paid			12,430	20,247	35,106	42,979		37,531		27,074
Income taxes paid, net of refunds			11,928	29,901	46,423	76,975		79,504		58,968
Supplemental disclosure of non-cash information:
Equipment acquired under capital lease			8,240	44,574	55,488	64,618		86,330		60,648
2011 Senior Convertible Notes [Member]
Supplemental disclosure of non-cash information:
Premium shares, conversion of convertible notes				114,785	114,785	155,744
Earn-Out Arrangements [Member]
Supplemental disclosure of non-cash information:
Acquisition-related contingent consideration, new business combinations			8,700	33,612	34,988	33,612		32,451		66,700
Machinery and Equipment [Member]
Supplemental disclosure of non-cash information:
Equipment acquired under financing arrangements			5,780	5,780	6,851	11,105		24,244		$ 6,009
As Reported [Member]
Cash flows from operating activities:
Net income	45,410	31,914	16,068	47,982	93,392
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	41,747	36,755	33,494	70,249	111,996
Non-cash interest expense			2,362	4,642	6,052
Non-cash stock-based compensation expense			3,260	7,480	11,584
Excess tax benefit from stock-based compensation			(3,246)	(3,386)	(3,494)
Provision for deferred income taxes			3,281	11,160	4,294
Other non-cash items			623	438	1,136
(Gains) losses on sales of assets, including impairment charges on discontinued operations			(1,622)	(2,593)	(4,068)
Changes in assets and liabilities, net of acquisitions:
Accounts receivable			(43,440)	(21,270)	(131,175)
Inventories			(13,313)	(37,140)	(27,553)
Other assets, current and long-term portion			9,034	4,655	5,202
Accounts payable and accrued expenses			(14,683)	(8,916)	14,521
Billings in excess of costs and earnings			(12,247)	(12,258)	4,171
Book overdrafts			1,266	(1,355)	(10,399)
Other liabilities, current and long-term portion			(1,231)	(4,369)	5,360
Net cash provided by operating activities			(20,394)	55,319	81,019
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired			(23,831)	(162,901)	(162,901)
Capital expenditures			(35,554)	(67,566)	(90,962)
Proceeds from sale of property and equipment			3,373	8,752	12,204
Proceeds from disposal of business, net of cash divested					0
(Payments for) proceeds from other investments			(1,098)	573	(1,046)
Net cash used in investing activities			(57,110)	(221,142)	(242,705)
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities			233,872	815,840	1,319,623
Repayments of credit facilities			(157,349)	(463,713)	(955,151)
Repayment of senior notes, including convertible notes				(105,325)	(105,325)
Repayments of other borrowings			(2,830)	(7,220)	(15,827)
Payments of capital lease obligations			(10,956)	(23,023)	(38,358)
Payments of tax withholdings and proceeds from stock-based awards, net			(1,451)	(578)	318
Excess tax benefit from stock-based compensation			3,246	3,386	3,494
Payments of acquisition-related contingent consideration				(58,902)	(60,341)
Payments of financing costs			(218)	(1,298)	(1,455)
Net cash provided by (used in) financing activities			64,314	159,167	146,978
Effect of currency translation on cash			(476)	(347)	(1,152)
Net increase (decrease) in cash and cash equivalents			(13,666)	(7,003)	(15,860)
Cash and cash equivalents - beginning of period	15,924	9,261	22,927	22,927	22,927	22,927
Cash and cash equivalents - end of period	7,067	15,924	9,261	15,924	7,067			22,927
Supplemental cash flow information:
Interest paid			12,430	20,247	35,106
Income taxes paid, net of refunds			11,928	29,901	46,423
Supplemental disclosure of non-cash information:
Equipment acquired under capital lease			8,240	44,574	55,488
As Reported [Member] | 2011 Senior Convertible Notes [Member]
Supplemental disclosure of non-cash information:
Premium shares, conversion of convertible notes				114,785	114,785
As Reported [Member] | Earn-Out Arrangements [Member]
Supplemental disclosure of non-cash information:
Acquisition-related contingent consideration, new business combinations			8,700	33,612	34,988
As Reported [Member] | Machinery and Equipment [Member]
Supplemental disclosure of non-cash information:
Equipment acquired under financing arrangements			5,780	5,780	6,851
Adjustments [Member]
Cash flows from operating activities:
Net income	3,715	1,675	(3,926)	(2,252)	1,463
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	0	0	0	0	0
Non-cash interest expense			0	0	0
Non-cash stock-based compensation expense			0	0	0
Excess tax benefit from stock-based compensation			0	0	0
Provision for deferred income taxes			0	0	0
Other non-cash items			0	0	0
(Gains) losses on sales of assets, including impairment charges on discontinued operations			0	0	0
Changes in assets and liabilities, net of acquisitions:
Accounts receivable			10,367	8,422	4,225
Inventories			0	0	0
Other assets, current and long-term portion			(2,426)	(1,382)	0
Accounts payable and accrued expenses			143	100	898
Billings in excess of costs and earnings			0	(837)	(1,275)
Book overdrafts			0	0	0
Other liabilities, current and long-term portion			(4,158)	(4,051)	(5,311)
Net cash provided by operating activities			0	0	0
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired			0	0	0
Capital expenditures			0	0	0
Proceeds from sale of property and equipment			0	0	0
Proceeds from disposal of business, net of cash divested					0
(Payments for) proceeds from other investments			0	0	0
Net cash used in investing activities			0	0	0
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities			0	0	0
Repayments of credit facilities			0	0	0
Repayment of senior notes, including convertible notes				0	0
Repayments of other borrowings			0	0	0
Payments of capital lease obligations			0	0	0
Payments of tax withholdings and proceeds from stock-based awards, net			0	0	0
Excess tax benefit from stock-based compensation			0	0	0
Payments of acquisition-related contingent consideration				0	0
Payments of financing costs			0	0	0
Net cash provided by (used in) financing activities			0	0	0
Effect of currency translation on cash			0	0	0
Net increase (decrease) in cash and cash equivalents			0	0	0
Cash and cash equivalents - beginning of period	0	0	0	0	0	$ 0
Cash and cash equivalents - end of period	$ 0	$ 0	0	0	0			$ 0
Supplemental cash flow information:
Interest paid			0	0	0
Income taxes paid, net of refunds			0	0	0
Supplemental disclosure of non-cash information:
Equipment acquired under capital lease			0	0	0
Adjustments [Member] | 2011 Senior Convertible Notes [Member]
Supplemental disclosure of non-cash information:
Premium shares, conversion of convertible notes				0	0
Adjustments [Member] | Earn-Out Arrangements [Member]
Supplemental disclosure of non-cash information:
Acquisition-related contingent consideration, new business combinations			0	0	0
Adjustments [Member] | Machinery and Equipment [Member]
Supplemental disclosure of non-cash information:
Equipment acquired under financing arrangements			$ 0	$ 0	$ 0

[1] Excess tax benefits, which represent cash flows from tax deductions in excess of the tax effect of compensation expense associated with exercised stock options and vested restricted shares, are classified as financing cash flows in the Company’s consolidated statements of cash flows.