Contingencies - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended			9 Months Ended
	Jun. 30, 2015 USD ($)	Dec. 31, 2012 Clinic	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Other Commitments [Line Items]
Loss contingency liability			$ 51,000			$ 51,000		$ 69,000
Gain on litigation settlement			$ 0		$ 0	$ 526,827	$ 0
Dialysis and other businesses
Other Commitments [Line Items]
Number of businesses acquired | Clinic		2
US Department Of Veterans Affairs Suit
Other Commitments [Line Items]
Litigation settlement amount				$ 538,000
Gain on litigation settlement				527,000
Vainer Private Civil Suit
Other Commitments [Line Items]
Litigation settlement amount	$ 450,000
Legal fees	$ 45,000
Noncontrolling Interest | US Department Of Veterans Affairs Suit
Other Commitments [Line Items]
Gain on litigation settlement				9,000
Operating Income (Loss) | US Department Of Veterans Affairs Suit
Other Commitments [Line Items]
Gain on litigation settlement				530,000
Equity Method Investments | Noncontrolling Interest | US Department Of Veterans Affairs Suit
Other Commitments [Line Items]
Gain on litigation settlement				$ 3,000