Business Combinations and Other Investments - Formation of Joint Business Entity and Acquisition of Netsmart, Inc. - Additional Information (Detail) - USD ($)		12 Months Ended
	Apr. 19, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 02, 2016	Oct. 14, 2016
Business Acquisition [Line Items]
Contribution and investment agreement date		Mar. 20, 2016
Description of liquidation preference		The liquidation preference is equal to the greater of (i) a return of the original issue price plus a preferred return (accruing on a daily basis at the rate of 11% per annum and compounding annually on the last day of each calendar year) or (ii) the as-converted value of Class A Common Units in Nathan.
Preferred return percentage		11.00%
Equity ownership percentage	49.10%			100.00%	100.00%
Selling, General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Acquisition-related costs		$ 0	$ 4,100,000
Homecare Business [Member]
Business Acquisition [Line Items]
Escrow deposit related to the integration of homecare business	$ 15,000,000	$ 10,000,000
Escrow deposit period	4 years
GI Partners [Member]
Business Acquisition [Line Items]
Minority interest percentage	47.20%
Netsmart Management [Member]
Business Acquisition [Line Items]
Minority interest percentage	3.70%
Netsmart [Member]
Business Acquisition [Line Items]
Netsmart transaction completion date		Apr. 19, 2016
Business combination, purchase price	$ 950,000,000
Business combination, aggregate consideration	937,066,000
Extinguishment of debt	325,000,000
Accrued interest and fees	2,000,000
Decrease in accounts receivable, net acquired			3,600,000
Increase in prepaid expenses and other assets, acquired			300,000
Decrease in other assets, acquired			300,000
Increase in deferred taxes, net acquired			700,000
Decrease in other liabilities			600,000
Increase in the residual allocation to goodwill			$ 3,700,000
Netsmart [Member] | Nathan [Member]
Business Acquisition [Line Items]
Business combination, aggregate consideration	$ 937,000,000