Deferred tax assets (liabilities) (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets (liabilities):
State taxes	$ 1,001,754	$ 888,867
Stock options	1,784,524	1,685,965
Accrued payroll and related costs	185,130	208,576
Accrued hospital pool deficit	282,913	0
Net operating loss carryforward	7,069,776	0
Property and equipment	(1,286,452)	(2,009,313)
Acquired intangible assets	(28,626,943)	(44,036,361)
Other	(1,941,368)	(3,669,941)
Net deferred tax liabilities before valuation allowance	(21,530,666)	(46,932,207)
Valuation Allowance	(3,385,932)	0
Net deferred tax liabilities	$ (24,916,598)	$ (46,932,207)