Intangible Assets - Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Goodwill
Balance at the beginning of the year	$ 1,229,745	$ 1,225,871
Acquisition of businesses	4,962	3,874
Balance at the end of the year	1,234,707	1,229,745
Centers
Goodwill
Balance at the beginning of the year	1,141,871	1,137,997
Acquisition of businesses	4,962	3,874
Balance at the end of the year	1,146,833	1,141,871
Onsites
Goodwill
Balance at the beginning of the year	50,940	50,940
Acquisition of businesses	0	0
Balance at the end of the year	50,940	50,940
Other Businesses
Goodwill
Balance at the beginning of the year	36,934	36,934
Acquisition of businesses	0	0
Balance at the end of the year	$ 36,934	$ 36,934