Reportable Business Segments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	$ 224,013	$ 206,176	$ 430,970	$ 391,455
Interest expense	(15,621)	(15,099)	(31,078)	(28,848)
Stock-based compensation expense	(8,890)	(7,610)	(17,175)	(15,101)
Income before income taxes	211,425	193,711	405,710	367,428
Total
Reconciliation of segment operating income to consolidated income before income taxes
Segment operating income	242,525	223,044	467,426	424,579
Unallocated amount to segment
Reconciliation of segment operating income to consolidated income before income taxes
Interest expense	(15,621)	(15,099)	(31,078)	(28,848)
Interest Income	3,391	2,990	6,486	5,530
Stock-based compensation expense	(8,890)	(7,610)	(17,175)	(15,101)
Other costs, net	(9,980)	(9,614)	(19,949)	(18,732)
Income before income taxes	$ 211,425	$ 193,711	$ 405,710	$ 367,428