Equity securities classified as available-for-sale securities acquired.

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Unsecured short-term debt instrument issued by corporations which are highly liquid investments that are readily convertible to know amounts of cash and interest-bearing accounts that typically pay a higher interest rate and are FDIC insured.

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Description of the payment terms of the debt instrument (for example whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

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Proceeds from sales of marketable securities settled in subsequent period.

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Long-Term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership. This does not include advances to clients.

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Amount of equity securities categorized neither as held-to-maturity nor as trading.

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The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity.

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No definition available.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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The cash outflow to acquire equity securities classified as available-for-sale securities, because they are not classified as trading securities.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Identify the stated interest rate per the agreement, for example, leasing and debt arrangements between related parties.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Investments (Narrative) (Details)	1 Months Ended	3 Months Ended
Investments (Narrative) (Details)	Apr. 30, 2016 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 GBP (£)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 GBP (£)
Schedule of Investments [Line Items]
Commercial paper and money market investments		$ 442,900,000			$ 485,100,000
Marketable equity securities		433,787,000			$ 424,229,000
Cash paid for new marketable equity securities		0	$ 13,271,000
Marketable equity securities purchased		0	12,900,000
Gain on sales of marketable equity securities			1,800,000
Proceeds from sales of marketable equity securities		$ 0	$ 6,000,000
Proceeds from Q1 sales of marketable securities settled in April 2016	$ 1,600,000
Residential Home Health Illinois [Member] \| Residential Healthcare Group Inc [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage		40.00%		40.00%
Residential Hospice Illinois [Member] \| Residential Healthcare Group Inc [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage		42.50%		42.50%
Residential Healthcare Michigan hospital joint venture [Member] \| Residential Healthcare Group Inc [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage		40.00%		40.00%
Celtic Healthcare Allegheny Health Network Joint Venture [Member] \| Celtic Healthcare [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage		40.00%		40.00%
Revenue from Related Parties		$ 4,600,000
York Joint Venture [Member] \| York University [Member]
Schedule of Investments [Line Items]
Equity Method Investment, Ownership Percentage		45.00%		45.00%
Notes Receivable, Related Parties, Noncurrent \| £				£ 25,000,000
Advances to Affiliate \| £						£ 11,000,000
Loan Receivable, Payment Terms		25 years
Loan Receivable Fixed Interest Rate		7.00%