Stockholders' Equity (Summarized Information about Warrants Outstanding) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Class of Warrant or Right [Line Items]
Outstanding, ending balance	197,783	133,591
Stock Purchase Warrants 2010 Issuance [Member]
Class of Warrant or Right [Line Items]
Grant date	2010
Warrants issued	51,627
Exercise price, lower limit	$ 20.64
Exercise price, upper limit	$ 27.41
Fair value of warrants issued	$ 351
Outstanding, ending balance		1,886
Stock Purchase Warrants 2011 Issuance [Member]
Class of Warrant or Right [Line Items]
Grant date	2011
Warrants issued	9,324
Exercise price, lower limit	$ 27.53
Exercise price, upper limit	$ 33.14
Fair value of warrants issued	$ 79
Outstanding, ending balance	6,226	9,324
Stock Purchase Warrants 2012 Issuance [Member]
Class of Warrant or Right [Line Items]
Grant date	2012
Warrants issued	71,978
Exercise price, lower limit	$ 30.52
Exercise price, upper limit	$ 33.03
Fair value of warrants issued	$ 628
Outstanding, ending balance	49,975	71,978
Stock Purchase Warrants 2014 Issuance [Member]
Class of Warrant or Right [Line Items]
Grant date	2014
Warrants issued	50,403
Exercise price, lower limit	$ 45.62
Exercise price, upper limit	$ 49.06
Fair value of warrants issued	$ 276
Outstanding, ending balance	50,403	50,403
Stock Purchase Warrants 2015 Issuance [Member]
Class of Warrant or Right [Line Items]
Grant date	2015
Warrants issued	91,179
Exercise price, lower limit	$ 42.45
Exercise price, upper limit	$ 54.48
Fair value of warrants issued	$ 1,333
Outstanding, ending balance	91,179