Amtrak Agreement - Schedule of Remaining Track Mileage Credit (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Agreement With Related Party [Abstract]
Mileage credit available	$ 418,000	$ 1,219,000
Utilized	418,000	801,000
Mileage credit remaining	$ 0	$ 418,000