Business Combinations (Acquired Intangible Assets and Weighted-Average Useful Lives) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2011
Total acquired identifiable intangible assets	$ 83,760
Weighted-average useful life of acquired identifiable intangible assets (years)	5.7
Customer Relationships [Member]
Total acquired identifiable intangible assets	43,900
Weighted-average useful life of acquired identifiable intangible assets (years)	6.4
Technology [Member]
Total acquired identifiable intangible assets	27,500
Weighted-average useful life of acquired identifiable intangible assets (years)	5.0
State DMV Contractual Relationships [Member]
Total acquired identifiable intangible assets	6,190
Weighted-average useful life of acquired identifiable intangible assets (years)	6.0
Non-compete Agreements [Member]
Total acquired identifiable intangible assets	5,180
Weighted-average useful life of acquired identifiable intangible assets (years)	3.0
Trade Names [Member]
Total acquired identifiable intangible assets	$ 990
Weighted-average useful life of acquired identifiable intangible assets (years)	3.0