Selected Consolidated Financial Statements of Parent, Guarantors, Canada Company and Non-Guarantors - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations			$ 393,806	$ 322,040
Cash Flows from Operating Activities—Discontinued Operations			(477)	(2,363)
Cash Flows from Operating Activities			393,329	319,677
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)	$ (121,996)	$ (92,005)	(217,601)	(165,207)
Cash paid for acquisitions, net of cash acquired	(237,895)	(26,036)	(1,666,869)	(38,223)
Payments to Fund Long-term Loans to Related Parties				0
Intercompany loans to subsidiaries			0
Investment in subsidiaries			0	0
Acquisitions of customer relationships and customer inducements		(7,107)	(37,233)	(28,510)
Net proceeds from Divestments (see Note 10)			0	2,423
Proceeds from sales of property and equipment and other, net (including real estate)			207	8,547
Cash Flows from Investing Activities—Continuing Operations			(1,921,496)	(220,970)
Cash Flows from Investing Activities—Discontinued Operations			0	0
Cash Flows from Investing Activities			(1,921,496)	(220,970)
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt			(7,876,796)	(5,751,416)
Proceeds from revolving credit, term loan facilities and other debt			8,944,416	5,494,125
Net proceeds from sales of senior notes			0	332,683
Borrowings under cash pools			0	0
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net			(1,079)	10,151
Intercompany loans from parent			0	0
Equity contribution from parent				0
Parent cash dividends			(337,052)	(147,393)
Net proceeds (payments) associated with employee stock-based awards			(2,259)	810
Net proceeds associated with the Over-Allotment Option (see Note 9)			76,192	0
Proceeds From Issuance Of At The Market Program			8,716	0
Payment of debt financing and stock issuance costs			(13,385)	(544)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations			798,753	(61,584)
Cash Flows from Financing Activities—Discontinued Operations			0	0
Net Cash Provided by (Used in) Financing Activities			798,753	(61,584)
Effect of exchange rates on cash and cash equivalents			(8,093)	17,412
(Decrease) Increase in cash and cash equivalents			(737,507)	54,535
Cash and cash equivalents, beginning of period			925,699	236,484
Cash and cash equivalents, end of period	188,192	291,019	188,192	291,019
Eliminations
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations			0	0
Cash Flows from Operating Activities—Discontinued Operations			0	0
Cash Flows from Operating Activities			0	0
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)			0	0
Cash paid for acquisitions, net of cash acquired			0	0
Payments to Fund Long-term Loans to Related Parties				(93,235)
Intercompany loans to subsidiaries			(389,515)
Investment in subsidiaries			0	16,170
Acquisitions of customer relationships and customer inducements			0	0
Net proceeds from Divestments (see Note 10)				0
Proceeds from sales of property and equipment and other, net (including real estate)			0	0
Cash Flows from Investing Activities—Continuing Operations			(389,515)	109,405
Cash Flows from Investing Activities—Discontinued Operations			0	0
Cash Flows from Investing Activities			(389,515)	109,405
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt			0	0
Proceeds from revolving credit, term loan facilities and other debt			0	0
Net proceeds from sales of senior notes				0
Borrowings under cash pools			4,807	(161,550)
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net			0	0
Intercompany loans from parent			389,515	(93,235)
Equity contribution from parent				(16,170)
Parent cash dividends			0	0
Net proceeds (payments) associated with employee stock-based awards			0	0
Net proceeds associated with the Over-Allotment Option (see Note 9)			0
Proceeds From Issuance Of At The Market Program			0
Payment of debt financing and stock issuance costs			0	0
Net Cash Provided by (Used in) Financing Activities, Continuing Operations			394,322	(270,955)
Cash Flows from Financing Activities—Discontinued Operations			0	0
Net Cash Provided by (Used in) Financing Activities			394,322	(270,955)
Effect of exchange rates on cash and cash equivalents			0	0
(Decrease) Increase in cash and cash equivalents			4,807	(161,550)
Cash and cash equivalents, beginning of period			(94,726)	0
Cash and cash equivalents, end of period	(89,919)	(161,550)	(89,919)	(161,550)
Parent | Reportable legal entities
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations			(117,979)	(81,406)
Cash Flows from Operating Activities—Discontinued Operations			0	0
Cash Flows from Operating Activities			(117,979)	(81,406)
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)			0	0
Cash paid for acquisitions, net of cash acquired			0	0
Payments to Fund Long-term Loans to Related Parties				51,119
Intercompany loans to subsidiaries			370,423
Investment in subsidiaries			0	(16,170)
Acquisitions of customer relationships and customer inducements			0	0
Net proceeds from Divestments (see Note 10)				0
Proceeds from sales of property and equipment and other, net (including real estate)			0	0
Cash Flows from Investing Activities—Continuing Operations			370,423	(67,289)
Cash Flows from Investing Activities—Discontinued Operations			0	0
Cash Flows from Investing Activities			370,423	(67,289)
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt			0	(262,579)
Proceeds from revolving credit, term loan facilities and other debt			0	224,660
Net proceeds from sales of senior notes				332,683
Borrowings under cash pools			0	0
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net			0	0
Intercompany loans from parent			0	0
Equity contribution from parent				0
Parent cash dividends			(337,052)	(147,393)
Net proceeds (payments) associated with employee stock-based awards			(2,259)	810
Net proceeds associated with the Over-Allotment Option (see Note 9)			76,192
Proceeds From Issuance Of At The Market Program			8,716
Payment of debt financing and stock issuance costs			(412)	(471)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations			(254,815)	147,710
Cash Flows from Financing Activities—Discontinued Operations			0	0
Net Cash Provided by (Used in) Financing Activities			(254,815)	147,710
Effect of exchange rates on cash and cash equivalents			0	0
(Decrease) Increase in cash and cash equivalents			(2,371)	(985)
Cash and cash equivalents, beginning of period			2,433	2,405
Cash and cash equivalents, end of period	62	1,420	62	1,420
Guarantors | Reportable legal entities
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations			409,167	305,548
Cash Flows from Operating Activities—Discontinued Operations			(477)	(957)
Cash Flows from Operating Activities			408,690	304,591
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)			(142,737)	(124,559)
Cash paid for acquisitions, net of cash acquired			(1,314,370)	(6,380)
Payments to Fund Long-term Loans to Related Parties				41,642
Intercompany loans to subsidiaries			19,092
Investment in subsidiaries			0	0
Acquisitions of customer relationships and customer inducements			(24,922)	(26,924)
Net proceeds from Divestments (see Note 10)				0
Proceeds from sales of property and equipment and other, net (including real estate)			0	12,933
Cash Flows from Investing Activities—Continuing Operations			(1,462,937)	(186,572)
Cash Flows from Investing Activities—Discontinued Operations			0	0
Cash Flows from Investing Activities			(1,462,937)	(186,572)
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt			(3,657,315)	(3,197,148)
Proceeds from revolving credit, term loan facilities and other debt			4,531,603	2,913,810
Net proceeds from sales of senior notes				0
Borrowings under cash pools			(7,657)	136,379
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net			0	0
Intercompany loans from parent			(384,323)	44,957
Equity contribution from parent				0
Parent cash dividends			0	0
Net proceeds (payments) associated with employee stock-based awards			0	0
Net proceeds associated with the Over-Allotment Option (see Note 9)			0
Proceeds From Issuance Of At The Market Program			0
Payment of debt financing and stock issuance costs			(12,322)	0
Net Cash Provided by (Used in) Financing Activities, Continuing Operations			469,986	(102,002)
Cash Flows from Financing Activities—Discontinued Operations			0	0
Net Cash Provided by (Used in) Financing Activities			469,986	(102,002)
Effect of exchange rates on cash and cash equivalents			0	0
(Decrease) Increase in cash and cash equivalents			(584,261)	16,017
Cash and cash equivalents, beginning of period			634,317	23,380
Cash and cash equivalents, end of period	50,056	39,397	50,056	39,397
Non-Guarantors | Reportable legal entities
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations				69,922
Cash Flows from Operating Activities—Discontinued Operations				(1,406)
Cash Flows from Operating Activities				68,516
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)				(36,477)
Cash paid for acquisitions, net of cash acquired				(31,843)
Payments to Fund Long-term Loans to Related Parties				474
Investment in subsidiaries				0
Acquisitions of customer relationships and customer inducements				(1,176)
Net proceeds from Divestments (see Note 10)				2,423
Proceeds from sales of property and equipment and other, net (including real estate)				(4,388)
Cash Flows from Investing Activities—Continuing Operations				(71,935)
Cash Flows from Investing Activities—Discontinued Operations				0
Cash Flows from Investing Activities				(71,935)
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt				(2,291,638)
Proceeds from revolving credit, term loan facilities and other debt				2,355,655
Net proceeds from sales of senior notes				0
Borrowings under cash pools				25,171
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net				10,151
Intercompany loans from parent				91,367
Equity contribution from parent				16,170
Parent cash dividends				0
Net proceeds (payments) associated with employee stock-based awards				0
Payment of debt financing and stock issuance costs				0
Net Cash Provided by (Used in) Financing Activities, Continuing Operations				206,876
Cash Flows from Financing Activities—Discontinued Operations				0
Net Cash Provided by (Used in) Financing Activities				206,876
Effect of exchange rates on cash and cash equivalents				14,706
(Decrease) Increase in cash and cash equivalents				218,163
Cash and cash equivalents, beginning of period				193,589
Cash and cash equivalents, end of period		411,752		411,752
Canada Company | Reportable legal entities
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations				27,976
Cash Flows from Operating Activities—Discontinued Operations				0
Cash Flows from Operating Activities				27,976
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)				(4,171)
Cash paid for acquisitions, net of cash acquired				0
Payments to Fund Long-term Loans to Related Parties				0
Investment in subsidiaries				0
Acquisitions of customer relationships and customer inducements				(410)
Net proceeds from Divestments (see Note 10)				0
Proceeds from sales of property and equipment and other, net (including real estate)				2
Cash Flows from Investing Activities—Continuing Operations				(4,579)
Cash Flows from Investing Activities—Discontinued Operations				0
Cash Flows from Investing Activities				(4,579)
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt				(51)
Proceeds from revolving credit, term loan facilities and other debt				0
Net proceeds from sales of senior notes				0
Borrowings under cash pools				0
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net				0
Intercompany loans from parent				(43,089)
Equity contribution from parent				0
Parent cash dividends				0
Net proceeds (payments) associated with employee stock-based awards				0
Payment of debt financing and stock issuance costs				(73)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations				(43,213)
Cash Flows from Financing Activities—Discontinued Operations				0
Net Cash Provided by (Used in) Financing Activities				(43,213)
Effect of exchange rates on cash and cash equivalents				2,706
(Decrease) Increase in cash and cash equivalents				(17,110)
Cash and cash equivalents, beginning of period				17,110
Cash and cash equivalents, end of period		$ 0		$ 0
Non-Guarantor Subsidiaries including Canada Company [Member] | Reportable legal entities
Cash Flows from Operating Activities:
Cash Flows from Operating Activities—Continuing Operations			102,618
Cash Flows from Operating Activities—Discontinued Operations			0
Cash Flows from Operating Activities			102,618
Cash Flows from Investing Activities:
Capital expenditures (see Liquidity and Capital Resources section of Management's Discussion & Analysis of Financial Condition and Results of Operations)			(74,864)
Cash paid for acquisitions, net of cash acquired			(352,499)
Intercompany loans to subsidiaries			0
Investment in subsidiaries			0
Acquisitions of customer relationships and customer inducements			(12,311)
Proceeds from sales of property and equipment and other, net (including real estate)			207
Cash Flows from Investing Activities—Continuing Operations			(439,467)
Cash Flows from Investing Activities—Discontinued Operations			0
Cash Flows from Investing Activities			(439,467)
Cash Flows from Financing Activities:
Repayment of revolving credit, term loan facilities and other debt			(4,219,481)
Proceeds from revolving credit, term loan facilities and other debt			4,412,813
Borrowings under cash pools			2,850
Debt financing from (repayment to) and equity contribution from (distribution to) noncontrolling interests, net			(1,079)
Intercompany loans from parent			(5,192)
Parent cash dividends			0
Net proceeds (payments) associated with employee stock-based awards			0
Net proceeds associated with the Over-Allotment Option (see Note 9)			0
Proceeds From Issuance Of At The Market Program			0
Payment of debt financing and stock issuance costs			(651)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations			189,260
Cash Flows from Financing Activities—Discontinued Operations			0
Net Cash Provided by (Used in) Financing Activities			189,260
Effect of exchange rates on cash and cash equivalents			(8,093)
(Decrease) Increase in cash and cash equivalents			(155,682)
Cash and cash equivalents, beginning of period			383,675
Cash and cash equivalents, end of period	$ 227,993		$ 227,993