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Long-Term Investments - Summary of Available-for-Sale Securities (Detail) - Failed Auction Security [Member] - USD ($)
Mar. 31, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Cost $ 3,000,000 $ 3,000,000
Gross Unrealized Gains 0 0
Gross unrealized losses 474,000 492,000
Estimated Fair Value $ 2,526,000 $ 2,508,000