Consolidated Condensed Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
OPERATING REVENUE	$ 163,606	$ 156,348	$ 472,044	$ 445,339
OPERATING EXPENSES (INCOME):
Salaries, wages and benefits	42,352	37,775	120,021	108,287
Purchased transportation	32,428	31,354	92,021	89,362
Fuel and fuel taxes	43,020	40,590	121,659	115,845
Supplies and maintenance	10,581	11,030	29,958	30,466
Depreciation	15,537	14,758	45,114	42,358
Operating taxes and licenses	1,694	1,644	4,893	4,577
Insurance and claims	4,809	4,617	15,816	13,330
Communications and utilities	1,265	1,168	3,637	3,396
Gain on disposition of revenue equipment	(1,349)	(1,084)	(4,053)	(2,819)
Other	3,429	3,385	10,336	10,458
Total operating expenses	153,766	145,237	439,402	415,260
OPERATING INCOME	9,840	11,111	32,642	30,079
NET INTEREST INCOME	(6)	(18)	(40)	(6)
INCOME BEFORE INCOME TAXES	9,846	11,129	32,682	30,085
Less: Income before income taxes attributable to noncontrolling interest	61	318	467	708
INCOME BEFORE INCOME TAXES ATTRIBUTABLE TO MARTEN TRANSPORT, LTD.	9,785	10,811	32,215	29,377
PROVISION FOR INCOME TAXES	3,267	4,478	12,667	12,755
NET INCOME	$ 6,518	$ 6,333	$ 19,548	$ 16,622
BASIC EARNINGS PER COMMON SHARE (in Dollars per share)	$ 0.30	$ 0.29	$ 0.89	$ 0.76
DILUTED EARNINGS PER COMMON SHARE (in Dollars per share)	$ 0.29	$ 0.29	$ 0.88	$ 0.75
DIVIDENDS PAID PER COMMON SHARE (in Dollars per share)	$ 0.025	$ 0.02	$ 0.07	$ 0.06