Valuation and Qualifying Accounts (Detail) (Allowance for Doubtful Accounts, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 250,343	$ 235,629	$ 229,317
DSI Renal Inc. Acquisition	7,752	16,193
Amounts charged to income	243,377	198,750	171,250
Amounts written off	256,350	200,229	164,938
Balance at end of year	$ 245,122	$ 250,343	$ 235,629