Debt Obligations (Details) $ / shares in Units, $ in Thousands	2 Months Ended	3 Months Ended	10 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Oct. 16, 2018	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Oct. 17, 2018 USD ($)	Oct. 30, 2014 USD ($) $ / shares	Apr. 09, 2014 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Convertible, Carrying Amount of Equity Component								$ 66,100
Term Loan, Due 2019	$ 0	$ 0		$ 0	$ 51,094
Revolving Credit Agreements, due 2019	215,725	215,725		215,725	3,000
Line of Credit Facility, Fair Value of Amount Outstanding	215,725	215,725		215,725	54,094
Convertible Debt	379,859	379,859		379,859	369,259
Total Debt Obligations	634,097	634,097		634,097	451,116
Unamortized Debt Issuance Expense	(6,298)	(6,298)		(6,298)	(5,816)
Carrying value of debt	627,799	627,799		627,799	445,300
Long-term Debt, Current Maturities	(38,017)	(38,017)		(38,017)	(41,288)
Long-term Debt, Excluding Current Maturities	589,782	589,782		589,782	$ 404,012
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	500	500		500
Long-term Debt, Maturities, Repayments of Principal in Year Two	401,500	401,500		401,500
Long-term Debt, Maturities, Repayments of Principal in Year Five	215,725	215,725		215,725
Long-term Debt, Maturities, Repayments of Principal in Year Three	0	0		0
Long-term Debt, Maturities, Repayments of Principal in Year Four	$ 0	$ 0		$ 0
Line of Credit Facility, Maximum Borrowing Capacity							$ 1,000,000		$ 675,000
Long-term Debt, Weighted Average Interest Rate, at Point in Time					2.90%
Line of Credit Facility, Interest Rate at Period End	3.10%	3.10%		3.10%	2.80%
Debt Instrument, Interest Rate Terms			The base rate is the highest of (i) the Bank of America prime rate, (ii) the Federal Funds rate plus 0.50% or (iii) the Fixed LIBOR rate plus 1.00%.
Letter of credit, interest rate at period end	1.10%	1.10%		1.10%	1.40%
Letters of Credit Outstanding, Amount	$ 77,800	$ 77,800		$ 77,800
Debt Instrument, Convertible, Conversion Price | $ / shares								$ 72.18
Debt Conversion, Original Debt, Amount		1,000
Debt Instrument, Face Amount								$ 402,500
Other debt obligations	38,513	38,513		38,513	$ 27,763
Other debt, current	38,017	38,017		38,017
Long-term Debt, Maturities, Repayments of Principal after Year Five	0	0		0
1.5% Issue [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Gross								$ 10,700
Debt Instrument, Interest Rate, Stated Percentage								1.50%
Debt Instrument, Unamortized Discount	21,600	21,600		21,600	33,200
Amortization of Debt Discount (Premium)				$ 11,500	$ 11,000	$ 10,400
Debt Instrument, Convertible, Effective Interest Rate				4.70%	4.70%
Debt Instrument, Convertible, Interest Expense				$ 6,000	$ 6,000	$ 6,000
Term Loan [Member]
Debt Instrument [Line Items]
Term Loan, Due 2019									75,000
Line of Credit [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount	$ 47,100	$ 47,100		$ 47,100	$ 57,300
Line of credit - India [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity									10,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity									$ 590,000
Minimum [Member]
Debt Instrument [Line Items]
Consolidated Fixed Charge Coverage Ratio	4.0	4.0		4.0
Maximum [Member]
Debt Instrument [Line Items]
Consolidated Total Leverage Ratio	3.5	3.5		3.5
Letter of Credit [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 200,000	$ 200,000		$ 200,000
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.125%		1.375%
London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%		2.375%
Base rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.175%		0.375%
Base rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%		1.375%
United States of America, Dollars | Swingline loans [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 50,000	50,000		50,000
Euro Member Countries, Euro | Swingline loans [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 90,000	$ 90,000		$ 90,000