Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 548,375	$ 534,140
Adjusted EBITDA	54,214	52,066
Capital Expenditures	19,801	16,668
Total assets	1,315,711		1,182,993
International [Member]
Segment Reporting Information [Line Items]
Revenues	249,863	244,769
Adjusted EBITDA	20,466	22,031
Capital Expenditures	8,355	5,984
Total assets	765,428
Americas [Member]
Segment Reporting Information [Line Items]
Revenues	298,512	289,371
Adjusted EBITDA	33,748	30,035
Capital Expenditures	11,446	10,684
Total assets	$ 550,283