Consolidated Statements of Operations (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenues from affiliates included in manufacturing	$ 245,891	$ 250,455	$ 103,679
Revenues from affiliates included in railcar services	19,304	17,167	21,442
Interest income from related parties	$ 2,429	$ 2,678	$ 2,902