Segment Information - Summary of Revenue by Product Type (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Product Information [Line Items]
Revenue	$ 14,268	$ 8,307
Core [Member]
Product Information [Line Items]
Revenue	11,355	987
Polished [Member]
Product Information [Line Items]
Revenue	1,095	6,057
Optical [Member]
Product Information [Line Items]
Revenue	1,638	1,144
Research And Development [Member]
Product Information [Line Items]
Revenue	125	98
Other [Member]
Product Information [Line Items]
Revenue	$ 55	$ 21