Long-Term Debt (Convertible Debt) - Additional Information (Detail)		12 Months Ended
	Mar. 11, 2015 USD ($)	Dec. 31, 2015 USD ($) $ / shares
Debt Instrument [Line Items]
Amount of loan issued		$ 173,700,000
Initial conversion price per share | $ / shares		$ 68.90
Unamortized debt discount of notes		$ 5,240,278
4.50% Convertible Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Amount of loan issued	$ 75,000,000	$ 75,000,000
Debt Instrument Maturity Year	2020	2020
Interest rate on mortgage loan	4.50%	4.50%
Line of credit facility, maturity date	Mar. 15, 2020
Debt instrument conversion ratio		14.5136
Convertible notes principal amount		$ 1,000
Initial conversion price per share | $ / shares		$ 68.90
Unamortized debt discount of notes	$ 6,100,000	$ 5,200,000
Cash Discount for issuance of the notes	2,600,000
Equity component of the convertible notes issued	3,500,000	$ 2,100,000
Net proceeds from issuance of notes	72,400,000
Credit facility repayments	$ 47,500,000