Selected Quarterly Financial and Supplementary Data - Schedule of Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Gross sales	$ 178,682		$ 99,867		$ 119,054		$ 93,935		$ 156,943		$ 92,350		$ 106,379		$ 78,184		$ 491,538	$ 433,856	$ 374,150
Net revenues	177,866		99,399		118,638		94,741		156,187		92,979		106,635		77,525		490,644	433,326	374,613
Gross profit	79,167		37,602		48,557		38,899		66,261		35,680		45,945		29,079		204,225	176,965	123,798
Income from continuing operations	37,949	[1]	13,721	[1]	20,810	[1]	14,845	[1]	17,482	[2]	11,876	[2]	19,450	[2]	8,368	[2]	87,325	57,176	58,133
(Loss)/income from discontinued operations, net of tax	(565)	[3]	(4,503)	[3]	(316)	[3]	(263)	[3]	332	[3]	(129)	[3]	213	[3]	(375)	[3]	(5,647)	41	(830)
Net income	$ 37,384		$ 9,218		$ 20,494		$ 14,582		$ 17,814		$ 11,747		$ 19,663		$ 7,993		$ 81,678	$ 57,217	$ 57,303
Basic (in dollars per share)	$ 1.16	[4]	$ 0.29	[4]	$ 0.64	[4]	$ 0.46	[4]	$ 0.56	[4]	$ 0.37	[4]	$ 0.63	[4]	$ 0.26	[4]	$ 2.55	$ 1.82	$ 1.86
Diluted (in dollars per share)	$ 1.13		$ 0.28		$ 0.62		$ 0.44		$ 0.54	[4]	$ 0.36	[4]	$ 0.61	[4]	$ 0.25	[4]	$ 2.48	$ 1.76	$ 1.81
Basic (in shares)	32,240	[4]	32,149	[4]	32,063	[4]	31,886	[4]	31,661	[4]	31,471	[4]	31,344	[4]	31,198	[4]	32,086	31,420	30,763
Diluted (in shares)	33,107	[4]	32,999	[4]	32,926	[4]	32,771	[4]	32,784	[4]	32,593	[4]	32,440	[4]	32,158	[4]	32,969	32,555	31,643

[1] Income from continuing operations for the first, second, third, and fourth quarters includes $290 of expense, $154 of expense, a $47 benefit and $761 of expense, respectively, for restructuring related to the decision to sell our finished dosage form facility in Hyderabad, India.

[2] Income from continuing operations in the fourth quarter includes restructuring expenses of $15,573 and a tax benefit of $1,464 related to the decision to sell our finished dosage form facility in Hyderabad, India.

[3] Discontinued operations include charges for environmental remediation related to sites of divested businesses.

[4] Earnings per share calculations for each of the quarters are based on the weighted average number of shares outstanding for each period. As such, the sum of the quarters may not necessarily equal the earnings per share amount for the year.