Goodwill and Identifiable Assets (Acquired Intangible Assets) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Apr. 02, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Intangible Assets [Line Items]
Amortization of intangible assets		$ 18,540	$ 8,248	$ 44,689	$ 25,011
Intangible assets subject to amortization:
Gross Carrying Amount		483,462		483,462		$ 305,359
Accumulated Amortization		243,173		243,173		198,535
Net Carrying Amount		240,289		240,289		106,824
Intangible assets not subject to amortization:
Trademarks, Carrying Amount		262,268		262,268		245,942
Goodwill, Carrying Amount	$ 527,388	1,420,636		1,420,636		894,095
Intangible Assets, Gross (Excluding Goodwill)		745,730		745,730		551,301
Total
Intangible Assets, Net (Excluding Goodwill)		502,557		502,557		352,766
Customer Contractual Relationships
Intangible Assets [Line Items]
Estimated Useful Life	13 years
Intangible assets subject to amortization:
Gross Carrying Amount		343,707		343,707		202,588
Accumulated Amortization		135,739		135,739		119,272
Net Carrying Amount		207,968		$ 207,968		83,316
Customer Contractual Relationships | Minimum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				2 years
Customer Contractual Relationships | Maximum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				13 years
Contractor Relations [Member]
Intangible assets subject to amortization:
Gross Carrying Amount		71,121		$ 71,121		71,121
Accumulated Amortization		65,102		65,102		59,174
Net Carrying Amount		6,019		$ 6,019		11,947
Contractor Relations [Member] | Minimum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				2 years
Contractor Relations [Member] | Maximum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				5 years
Backlog [Member]
Intangible Assets [Line Items]
Estimated Useful Life	1 year
Intangible assets subject to amortization:
Gross Carrying Amount		26,100		$ 26,100		0
Accumulated Amortization		17,400		17,400		0
Net Carrying Amount		8,700		$ 8,700		0
Backlog [Member] | Minimum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				1 year
Non-compete agreements
Intangible assets subject to amortization:
Gross Carrying Amount		22,234		$ 22,234		11,850
Accumulated Amortization		8,950		8,950		6,600
Net Carrying Amount		13,284		$ 13,284		5,250
Non-compete agreements | Minimum [Member]
Intangible Assets [Line Items]
Estimated Useful Life	4 years			2 years
Non-compete agreements | Maximum [Member]
Intangible Assets [Line Items]
Estimated Useful Life	7 years			7 years
Favorable Contracts [Member]
Intangible Assets [Line Items]
Estimated Useful Life	5 years
Intangible assets subject to amortization:
Gross Carrying Amount		1,400		$ 1,400		900
Accumulated Amortization		804		804		673
Net Carrying Amount		596		$ 596		227
Favorable Contracts [Member] | Minimum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				5 years
Computer Software, Intangible Asset [Member]
Intangible assets subject to amortization:
Gross Carrying Amount		18,900		$ 18,900		18,900
Accumulated Amortization		15,178		15,178		12,816
Net Carrying Amount		$ 3,722		$ 3,722		$ 6,084
Computer Software, Intangible Asset [Member] | Minimum [Member]
Intangible Assets [Line Items]
Estimated Useful Life				6 years