Redeemable Non-Controlling Interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Changes in Carrying Amount (Fair Value) of Redeemable Non-Controlling Interests [Roll Forward]
Beginning balance	$ 102,572
Operating results allocated to redeemable non-controlling interest partners	8,433	$ 244	$ 0
Ending balance	133,943	102,572
Carrying Amount (Fair Value) of Redeemable Non-Controlling Interest [Abstract]
Contractual time period has lapsed but holder's employment has not been terminated				$ 0	$ 327
Contractual time period has not lapsed and holder's employment has not been terminated				0	0
Holder's employment has terminated and contractual time period has expired				0	0
Holder's employment has terminated and contractual time period has not expired				0	0
Redeemable non-controlling interests	133,943	102,572		133,943	102,572
Redeemable Non-Controlling Interest [Member]
Changes in Carrying Amount (Fair Value) of Redeemable Non-Controlling Interests [Roll Forward]
Beginning balance	102,572	0
Operating results allocated to redeemable non-controlling interest partners	8,433	244
Distributions to redeemable non-controlling interest partners	(9,835)	(272)
Changes in the fair value of redeemable non-controlling interest	24,770	201
Purchases of businesses - initial equity related to redeemable non-controlling interest	8,145	13,883
Fair value of redeemable non-controlling interest - amended partnership agreements	0	88,516
Other	(142)	0
Ending balance	133,943	102,572	0
Carrying Amount (Fair Value) of Redeemable Non-Controlling Interest [Abstract]
Contractual time period has lapsed but holder's employment has not been terminated				42,624	31,821
Contractual time period has not lapsed and holder's employment has not been terminated				91,319	70,751
Holder's employment has terminated and contractual time period has expired				0	0
Holder's employment has terminated and contractual time period has not expired				0	0
Redeemable non-controlling interests	$ 102,572	$ 102,572	$ 0	$ 133,943	$ 102,572
Therapy Practice [Member] | Minimum [Member]
Business Combination, Description [Abstract]
Business acquisition, percentage of limited partnership acquired				50.00%
Therapy Practice [Member] | Maximum [Member]
Business Combination, Description [Abstract]
Business acquisition, percentage of limited partnership acquired				90.00%
Therapy Practice [Member] | NewCo. [Member]
Business Combination, Description [Abstract]
Percentage of equity interest of subsidiary contributed for acquisition				100.00%
Business acquisition, percentage of general partnership interest acquired				100.00%
Business acquisition, consideration payable, term of note	2 years
Employment agreement renewal term	1 year
Non-Compete agreement term under condition of termination of employment of employed selling shareholder	2 years
Therapy Practice [Member] | NewCo. [Member] | Minimum [Member]
Business Combination, Description [Abstract]
Employment agreement term	3 years
Non-Compete agreement term regardless of whether the selling shareholder is employed	5 years
Therapy Practice [Member] | NewCo. [Member] | Maximum [Member]
Business Combination, Description [Abstract]
Employment agreement term	5 years
Non-Compete agreement term regardless of whether the selling shareholder is employed	6 years