Segment Information - Financial Information by Geographical Area (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment And Geographic Distribution Of Operations [Line Items]
Net revenue	$ 9,440,182	$ 9,071,532	$ 8,868,324
Long-Lived Assets	416,814	306,812
United States
Segment And Geographic Distribution Of Operations [Line Items]
Net revenue	8,951,852	8,688,018	8,731,484
Long-Lived Assets	260,694	170,010
United Kingdom
Segment And Geographic Distribution Of Operations [Line Items]
Net revenue	253,527	211,296	86,332
Long-Lived Assets	42,179	42,619
Ireland
Segment And Geographic Distribution Of Operations [Line Items]
Long-Lived Assets	29,018	0
France
Segment And Geographic Distribution Of Operations [Line Items]
Net revenue	54,656	52,725	14,338
Long-Lived Assets	6,395	7,090
Germany
Segment And Geographic Distribution Of Operations [Line Items]
Net revenue	47,682	42,807	13,670
Long-Lived Assets	55,437	60,068
Other European countries
Segment And Geographic Distribution Of Operations [Line Items]
Net revenue	132,465	76,686	22,500
Long-Lived Assets	$ 23,091	$ 27,025