Loan Receivables Held for Sale - Activities associated with loan receivable sales and servicing activities (Details) - USD ($) $ in Thousands				3 Months Ended	6 Months Ended
Jun. 27, 2018	May 21, 2018	Jun. 29, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Receivables [Abstract]
Gain/(loss) on sold loan receivables held for sale				$ 0	$ (88)	$ 0	$ (88)
Cash Flows
Sales of loans	$ 50,614	$ 9,552	$ 17,900	60,166	17,900	60,166	17,900
Servicing fees				$ 533	$ 811	$ 1,099	$ 1,711

Cash Flows between a transferor and a transferee attributable to newly transferred assets related to either a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107207-111719

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- Definition

Cash Flows between a transferee and a transferor attributable to servicing fees related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(4)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107207-111719

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- Definition

Reflects the net positive or negative amount derived from subtracting from net proceeds of sale and the carrying amounts, net of allocated reserves, of financial assets transferred to third parties in transactions that qualify for sales treatment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109247956&loc=d3e107425-111719

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- References

No definition available.

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- References

No definition available.

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