Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 29, 2013	Sep. 30, 2012
Current assets:
Cash and cash equivalents	$ 129,305	$ 104,848
Accounts receivable - net	660,847	700,480
Prepaid expenses and other current assets	61,446	48,168
Income taxes receivable	20,044	5,817
Total current assets	871,642	859,313
Property and equipment - net	88,026	74,309
Investments in and advances to unconsolidated joint ventures	2,198	3,279
Goodwill	722,792	635,958
Intangible assets - net	86,929	74,231
Other long-term assets	27,505	23,940
Total assets	1,799,092	1,671,030
Current liabilities:
Accounts payable	142,813	154,003
Accrued compensation	114,810	128,086
Billings in excess of costs on uncompleted contracts	79,507	90,909
Deferred income taxes	18,170	20,809
Current portion of long-term debt	4,311	2,031
Estimated contingent earn-out liabilities	23,281	35,407
Other current liabilities	100,241	72,549
Total current liabilities	483,133	503,794
Deferred income taxes	30,525	24,268
Long-term debt	203,438	81,047
Long-term estimated contingent earn-out liabilities	58,508	16,132
Other long-term liabilities	24,685	25,922
Commitments and contingencies
Equity:
Preferred stock - Authorized, 2,000 shares of $0.01 par value; no shares issued and outstanding at September 29, 2013, and September 30, 2012
Common stock - Authorized, 150,000 shares of $0.01 par value; issued and outstanding, 64,134 and 63,837 shares at September 29, 2013, and September 30, 2012, respectively	641	638
Additional paid-in capital	443,099	433,009
Accumulated other comprehensive income	1,858	31,017
Retained earnings	552,165	554,306
Tetra Tech stockholders' equity	997,763	1,018,970
Noncontrolling interests	1,040	897
Total equity	998,803	1,019,867
Total liabilities and equity	$ 1,799,092	$ 1,671,030