Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net earnings	$ 133,453	$ 99,533	$ 86,896
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation	45,729	34,212	27,712
Amortization of deferred costs	393	549	633
Loss (gain) on disposal of property, plant, equipment and leased railcars	154	(71)	24
(Earnings) loss from joint ventures	(5,812)	(1,570)	8,595
Provision for deferred income taxes	61,644	72,369	39,707
Provision for allowance for doubtful accounts receivable	234	1,064	48
Item related to investing activities:
Realized and unrealized gains on short-term investments—available for sale securities	0	0	(141)
Item related to financing activities:
Loss on debt extinguishment	2,126	1,896	392
Changes in operating assets and liabilities:
Accounts receivable, net	4,231	(12,779)	14,077
Accounts receivable, due from affiliates	23,518	(16,703)	(12,904)
Income taxes receivable	30,899	(31,576)	(2,316)
Inventories, net	19,812	(26,935)	19,819
Prepaid expenses and other current assets	1,206	(4,244)	(398)
Accounts payable	(32,630)	16,034	(12,184)
Accounts payable, due to related parties	1,683	1,383	(1,421)
Accrued expenses and taxes	(19,105)	639	5,468
Other	(3,032)	2,998	(9,241)
Net cash provided by operating activities	264,503	136,799	164,766
Investing activities:
Purchases of property, plant and equipment	(36,614)	(20,070)	(22,025)
Capital expenditures—leased railcars	(211,646)	(307,680)	(162,068)
Proceeds from the sale of property, plant, equipment and leased railcars	122	800	54
Proceeds from the sale of short-term investments—available for sale securities	0	0	12,699
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	(7,500)	(3,750)	(5,100)
Investments in and loans to joint ventures	0	0	(136)
Net cash used in investing activities	(240,638)	(323,200)	(166,376)
Financing activities:
Repayments of short-term and long-term debt	(432,645)	(204,486)	(180,083)
Proceeds from short-term and long-term debt	725,306	418,682	99,841
Change in interest reserve related to long-term debt	(9,739)	13	(3,908)
Stock repurchases	(57,423)	0	0
Payment of common stock dividends	(33,243)	(34,164)	(21,352)
Debt issuance costs	(5,857)	(2,566)	(543)
Net cash provided by (used in) financing activities	186,399	177,479	(106,045)
Effect of exchange rate changes on cash and cash equivalents	(309)	(221)	(138)
Increase (decrease) in cash and cash equivalents	209,955	(9,143)	(107,793)
Cash and cash equivalents at beginning of year	88,109	97,252
Cash and cash equivalents at end of year	$ 298,064	$ 88,109	$ 97,252