Segments and Operations by Geographic Area (Foreign Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 918,648	$ 738,257
Property and equipment, net	383,174		350,378
Goodwill and other intangible assets, net	956,899	822,700	961,807	825,500
Reportable Geographical Components [Member] | Foreign Operation [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	12,300		13,000
Goodwill and other intangible assets, net	29,600		31,300
Segment, Continuing Operations [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	918,600	738,300
Segment, Continuing Operations [Member] | Reportable Geographical Components [Member] | UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	878,900	676,000
Segment, Continuing Operations [Member] | Reportable Geographical Components [Member] | Foreign Operation [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	39,700	62,300
Property and equipment, net	10,700		11,500
Goodwill and other intangible assets, net	29,600		31,300
Segment, Discontinued Operations [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	6,300	40,200
Segment, Discontinued Operations [Member] | Reportable Geographical Components [Member] | UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	4,000	38,500
Segment, Discontinued Operations [Member] | Reportable Geographical Components [Member] | Foreign Operation [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,300	1,700
Property and equipment, net	1,600		1,500
Goodwill and other intangible assets, net	$ 0		$ 0