Related Party Transactions Interest Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Related Party Transaction [Line Items]
Senior Secured Notes Interest Expense-Related Party	$ 158	$ 0
Board of Directors Chairman [Member]
Related Party Transaction [Line Items]
Senior Secured Notes Interest Expense-Related Party	142	0
Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Senior Secured Notes Interest Expense-Related Party	$ 16	$ 0

Represents the portion of related party interest incurred in the period on notes which are collateralized by (i) first lien on (a) finance receivables held by the issuers, (b) equity interests held by DTAC in special purpose entities owned by an issuer or guarantor to the extent such equity interests are pledged as security for the Notes, and (c) residual property rights in finance receivables securing other financings of the issuers, in each case subject to certain exceptions and a (ii) second lien, behind one or more secured credit facilities on inventory owned by one of the guarantors.

No definition available.

Name:	dta_SeniorSecuredNotesInterestExpenseRelatedParty
Namespace Prefix:	dta_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration