Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net (loss) income	$ (223,359)	$ (35,603)	$ 11,058
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Recognition of deferred product revenue - Zanaflex			(22,186)
Share-based compensation expense	32,814	36,386	33,467
Amortization of net premiums and discounts on investments		467	3,366
Amortization of debt discount and debt issuance costs	12,153	9,717	8,562
Depreciation and amortization expense	23,234	21,582	15,012
Intangible asset impairment	296,763
Change in contingent consideration obligation	40,622	8,600	10,900
Gain on sale of Zanaflex franchise	(3,534)
Realized gain on foreign currency transaction	247	(9,856)
Restructuring costs, net of cash payments	1,472
Non-cash royalty revenue	(2,705)
Deferred tax (benefit) provision	(54,044)	(11,190)	3,975
Excess tax charge (benefit) from share-based compensation arrangements		15	(194)
Changes in assets and liabilities:
(Increase) decrease in accounts receivable	(29,112)	(19,965)	744
Decrease (increase) in prepaid expenses and other current assets	3,445	6,904	(998)
Decrease (increase) in inventory	5,505	(6,660)	(9,639)
Decrease in non-current portion of deferred cost of license revenue	634	634	634
Decrease in other assets	3,759	34	34
(Decrease) increase in accounts payable, accrued expenses and other current liabilities	(3,571)	37,625	(1,184)
Decrease in non-current portion of deferred license revenue	(9,057)	(9,057)	(9,057)
Increase (decrease) in other non-current liabilities	1,491	16	(198)
Decrease in deferred product revenue—Zanaflex			(989)
(Increase) decrease in restricted cash	(257)	5,698	(4,826)
Net cash provided by operating activities	96,500	35,347	38,481
Cash flows from investing activities:
Purchases of property and equipment	(13,688)	(6,192)	(5,921)
Purchases of intangible assets	(688)	(893)	(1,145)
Acquisitions, net of cash received and gain on foreign currency transaction		(266,454)
Net proceeds from sale of Zanaflex franchise	3,663
Purchases of investments		(40,215)	(434,670)
Proceeds from maturities of investments		239,968	356,500
Net cash used in investing activities	(10,713)	(73,786)	(85,236)
Cash flows from financing activities:
Debt issuance costs		(1,587)
Proceeds from issuance of common stock and option exercises	10,479	75,520	18,096
Repayment/(purchase) of non-controlling interest	2,722	(27,946)
Purchase of treasury stock	(60)
Net proceeds from royalty monetizations	50,787
Repayment of loans payable	(2,409)
Excess tax (benefit) charge from share-based compensation arrangements		(15)	194
Repayments of revenue interest liability		(41)	(501)
Net cash provided by financing activities	61,519	45,931	17,789
Effect of exchange rate changes on cash and cash equivalents	1,225	(2,159)
Net increase (decrease) in cash and cash equivalents	148,531	5,333	(28,966)
Cash and cash equivalents at beginning of period	158,537	153,204	182,170
Cash and cash equivalents at end of period	307,068	158,537	153,204
Supplemental disclosure:
Cash paid for interest	6,066	6,059	7,218
Cash paid for taxes	$ 14,929	$ 4,250	$ 4,697