Accounts Receivable (Schedule of Accounts Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross trade accounts receivable	$ 414,369	$ 383,347
Deductions from trade accounts receivable	(275,509)	(240,061)	(229,076)	(195,702)
Allowance for doubtful accounts	(255)	(7)	0	0
Accounts receivable, net	138,605	143,279
Chargebacks [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	(58,256)	(48,766)	(49,760)	(41,670)
Rebates and incentive programs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	(88,367)	(75,321)	(64,655)	(59,426)
Returns [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	(86,335)	(78,181)	(79,081)	(68,062)
Cash discounts and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deductions from trade accounts receivable	$ (42,551)	$ (37,793)	$ (35,580)	$ (26,544)