Short-term Investments - Available for Sale Securities (Details) - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sale of equity investments	$ 0	$ 0	$ 12,699
Greenbrier [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of shares sold during period (in shares)			0.8
Proceeds from sale of equity investments			$ 12,700
Realized gains			$ 2,000