CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Cash flows from operating activities:
Net income (loss)	$ 3,784	$ (20,684)
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Stock-based compensation	10,490	10,215
Depreciation	11,558	10,146
Amortization of intangibles	10,106	12,510
Amortization of deferred finance charges	1,480	7,999
Adjustment to deferred acquisition consideration	15,792	6,180
Deferred income tax	6,962	1,663
(Gain) loss on sale of assets	(63)	285
(Earnings) losses of non-consolidated affiliates	(502)	61
Other non-current assets and liabilities	(1,454)	3,519
Foreign exchange	(6,865)	(17,245)
Changes in working capital:
Accounts receivable	(67,889)	(60,217)
Expenditures billable to clients	(9,223)	(7,696)
Prepaid expenses and other current assets	6,511	(14,957)
Accounts payable, accruals and other liabilities	13,332	(109,028)
Advance billings	29,714	40,179
Net cash provided by (used in) operating activities	23,733	(110,197)
Cash flows used in investing activities:
Capital expenditures	(21,156)	(13,448)
Deposits	(1,261)	0
Acquisitions, net of cash acquired	0	(2,216)
Distributions from non-consolidated affiliates	(465)	(1,098)
Net Cash Provided by (Used in) Investing Activities	(22,882)	(16,762)
Cash flows provided by financing activities:
Acquisition related payments	(65,121)	(114,140)
Repayment of long-term debt	(224)	(272)
Purchase of shares	(630)	(2,474)
Premium paid on redemption of notes	0	(26,873)
Deferred financing costs	0	(20,329)
Distributions to noncontrolling interests	(3,840)	(5,413)
Payment of dividends	(169)	(21,525)
Net Cash Provided by (Used in) Financing Activities	(7,331)	81,372
Effect of exchange rate changes on cash and cash equivalents	(1,094)	191
Decrease in cash and cash equivalents	(7,574)	(45,396)
Cash and cash equivalents at beginning of period	27,921	61,458
Cash and cash equivalents at end of period	20,347	16,062
Supplemental disclosures:
Cash income taxes paid	3,423	807
Cash interest paid	31,566	30,600
Change in cash held in trusts	185	223
Non-cash transactions:
Capital leases	545	0
Dividends payable		966
Deferred acquisition consideration settled through issuance of shares	27,852
Six Point Seven Five Percentage Notes [Member]
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Loss on redemption of notes	0	26,873
Cash flows provided by financing activities:
Repayment of 6.75% Notes	0	735,000
Six Point Five Zero Percentage Notes [Domain]
Cash flows provided by financing activities:
Proceeds from issuance of 6.50% Notes	0	900,000
Wells Fargo Capital Finance, LLC | Revolving Credit Facility [Member]
Cash flows provided by financing activities:
Repayments of revolving credit agreement	(791,609)	(791,808)
Proceeds from revolving credit agreement	763,846	899,206
Common Stock [Member]
Non-cash transactions:
Deferred acquisition consideration settled through issuance of shares	28,727
Series 4 Convertible Preferred Stock [Domain]
Cash flows provided by financing activities:
Proceeds from issuance of convertible preference shares	95,000	0
Convertible Preferred Stock [Member]
Cash flows provided by financing activities:
Convertible preference shares issuance costs	$ (4,584)	0
Common Class A [Member] | Common Stock [Member]
Non-cash transactions:
Deferred acquisition consideration settled through issuance of shares		$ 5,585