Schedule II - Valuation and Qualifying Consolidated Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for Doubtful Accounts, Current [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 1,001	$ 50		$ 50
Additions Charged to Costs and Expenses	350	951
Balance at End of Year	1,351	1,001		50
Allowance for inventory [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	12,292	12,361	12,319
Additions Charged to Costs and Expenses	1,225		42
Deductions		69
Balance at End of Year	13,517	12,292	12,361
Allowance for contractual discounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	74,711	50,389	39,591
Additions Charged to Costs and Expenses	408,362	312,927	258,889
Deductions	386,483	288,605	248,091
Balance at End of Year	96,590	74,711	50,389
Allowance for uncompensated care [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	46,387	52,168	37,734
Additions Charged to Costs and Expenses	79,564	71,011	69,910
Deductions	84,093	76,792	55,476
Balance at End of Year	$ 41,858	$ 46,387	$ 52,168