Reportable Business Segments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 232,135	$ 206,957
Interest expense	(19,071)	(15,457)
Stock-based compensation expense	(9,276)	(8,283)
Acquisition-related expenses	(2,020)
Income before income taxes	217,129	194,285
Segment operating income
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	253,417	224,901
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense	(19,071)	(15,457)
Interest Income	4,445	3,095
Stock-based compensation expense	(9,276)	(8,283)
Acquisition-related expenses	(2,020)
Other costs, net	(10,366)	(9,971)
Income before income taxes	$ 217,129	$ 194,285

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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