Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Customer $ / shares	Dec. 31, 2014 USD ($) Customer $ / shares	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Schedule Of Accounting Policies [Line Items]
Common stock, stock split ratio	0.355872
Common stock, par value | $ / shares	$ 0.01	$ 0.01
Accrual for rebates and allowances	$ 2,300,000	$ 2,200,000
Rebate and allowance charges against gross revenues	5,900,000	5,200,000	$ 4,800,000
Allowances for doubtful accounts	900,000	600,000
Miscellaneous receivables	$ 1,000,000	$ 2,000,000
Number of clients accounting for 10% or more of net accounts receivable | Customer	3	3
Cost of goods sold	$ 157,939,000	$ 176,081,000	206,311,000
Capitalized inventories	0	0
Capitalized software development costs, net of accumulated amortization	9,137,000	2,421,000
Amortization expense	1,100,000	700,000	1,500,000
Estimated future amortization expense, 2016	5,165,000
Estimated future amortization expense, 2017	3,386,000
Estimated future amortization expense, 2018	2,683,000
Estimated future amortization expense, 2019	1,832,000
Estimated future amortization expense, 2020	1,592,000
Expense associated with the amortization of deferred financing costs	1,900,000	2,500,000	2,400,000
Write-off of deferred financing costs	236,000	2,392,000	598,000
Other long-term assets	20,414,000	20,578,000
Long-term debt	349,858,000	392,863,000
Face value of debt		400,000,000
Shipping and handling costs	17,400,000	19,400,000	20,500,000
Advertising and promotion costs	3,100,000	2,800,000	2,700,000
Total losses arising from foreign currency transactions	(1,752,000)	(279,000)	(349,000)
Asset retirement obligations	8,145,000	7,435,000	$ 6,385,000	$ 5,416,000
Accrued liabilities associated with employee medical costs	400,000	400,000
Balance in restricted cash account to fund medical claims	100,000	100,000
Capitalized Software [Member]
Schedule Of Accounting Policies [Line Items]
Estimated future amortization expense, 2016	2,200,000
Estimated future amortization expense, 2017	2,000,000
Estimated future amortization expense, 2018	2,000,000
Estimated future amortization expense, 2019	1,700,000
Estimated future amortization expense, 2020	$ 1,200,000
Minimum [Member]
Schedule Of Accounting Policies [Line Items]
Estimated useful life	3 years
Maximum [Member]
Schedule Of Accounting Policies [Line Items]
Estimated useful life	5 years
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes [Member]
Schedule Of Accounting Policies [Line Items]
Estimated fair value of debt		$ 384,000,000
Customer Concentration Risk [Member] | Revenues [Member]
Schedule Of Accounting Policies [Line Items]
Concentration risk percentage	12.00%	11.00%	10.00%
New Accounting Pronouncement, Early Adoption, Effect [Member] | Revolving Line of Credit [Member] | Other Current Assets [Member]
Schedule Of Accounting Policies [Line Items]
Deferred financing costs	$ 1,100,000	$ 900,000
Cardiolite [Member]
Schedule Of Accounting Policies [Line Items]
Cost of goods sold	$ 600,000
Neurolite [Member]
Schedule Of Accounting Policies [Line Items]
Cost of goods sold		1,900,000
Previously Reported [Member]
Schedule Of Accounting Policies [Line Items]
Common stock, par value | $ / shares	$ 0.001
Restatement Adjustment [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Schedule Of Accounting Policies [Line Items]
Other long-term assets	$ 5,500,000	(5,500,000)
Long-term debt	$ 6,400,000	$ (6,400,000)