Short term Investments - Available for Sale Securities (Details) (USD $) Share data in Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sale of equity	$ 0	$ 12,699,000
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		12,700,000
Realized gains		$ 2,000,000