Summary of Significant Accounting Policies (Details 7) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of intangible assets
Gross Carrying Amount	$ 175,583,000	$ 130,233,000
Accumulated Amortization	(105,889,000)	(95,298,000)
Net Carrying Amount	69,694,000	34,935,000
Amortization expense	10,600,000	9,700,000	10,700,000
Estimated amortization expense in future
2014	15,400,000
2015	14,000,000
2016	9,900,000
2017	6,100,000
2018	4,600,000
Customer agreements and lists
Summary of intangible assets
Gross Carrying Amount	163,990,000	121,490,000
Accumulated Amortization	(100,482,000)	(90,548,000)
Net Carrying Amount	63,508,000	30,942,000
Customer agreements and lists | Minimum
Summary of intangible assets
Estimated Useful Life	2 years 6 months	3 years
Customer agreements and lists | Maximum
Summary of intangible assets
Estimated Useful Life	18 years	18 years
Provider networks and other
Summary of intangible assets
Gross Carrying Amount	11,593,000	8,743,000
Accumulated Amortization	(5,407,000)	(4,750,000)
Net Carrying Amount	$ 6,186,000	$ 3,993,000
Provider networks and other | Minimum
Summary of intangible assets
Estimated Useful Life	1 year	5 years
Provider networks and other | Maximum
Summary of intangible assets
Estimated Useful Life	16 years	16 years