Summary of Significant Accounting Policies (Goodwill and Other Intangible Assets) (Details) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2015
Significant Accounting Policies [Line Items]
Goodwill impairment							$ 0
Goodwill allocated to sale of business					$ 7,000,000
Asset impairment	$ 1,900,000	$ 3,800,000	$ 84,700,000	$ 1,884,000	88,536,000	$ 0
Goodwill		558,886,000		558,886,000	558,886,000	565,900,000
Finite-Lived Intangible Assets
Gross Carrying Amount		71,000,000		71,000,000	71,000,000
Accumulated Amortization		(59,200,000)		(61,900,000)	(59,200,000)
Net Balance		11,800,000		9,100,000	11,800,000
Amortization expense				2,800,000	3,000,000	3,400,000
Future Amortization Expense
Estimated annual pretax amortization expense, 2016				2,200,000
Estimated annual pretax amortization expense, 2017				2,200,000
Estimated annual pretax amortization expense, 2018				2,100,000
Estimated annual pretax amortization expense, 2019				900,000
Estimated annual pretax amortization expense, 2020				600,000
Provider Networks [Member]
Finite-Lived Intangible Assets
Gross Carrying Amount		41,500,000		41,500,000	41,500,000
Accumulated Amortization		(36,900,000)		(38,000,000)	(36,900,000)
Net Balance		4,600,000		$ 3,500,000	$ 4,600,000
Weighted Average Life (in years)				18 years 10 months 24 days	18 years 10 months 24 days
Customer Relationships [Member]
Finite-Lived Intangible Assets
Gross Carrying Amount		29,500,000		$ 29,500,000	$ 29,500,000
Accumulated Amortization		(22,300,000)		(23,900,000)	(22,300,000)
Net Balance		7,200,000		$ 5,600,000	$ 7,200,000
Weighted Average Life (in years)				11 years 1 month 6 days	11 years 1 month 6 days
Western Region Operations [Member]
Significant Accounting Policies [Line Items]
Goodwill allocated to sale of business					$ 7,000,000
Goodwill		$ 558,900,000		$ 558,900,000	558,900,000	$ 565,900,000
Goodwill [Member]
Significant Accounting Policies [Line Items]
Asset impairment				$ 0	$ 7,000,000