Portfolio Loans - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) loan	Jun. 30, 2015 USD ($) loan	Jun. 30, 2016 USD ($) loan	Jun. 30, 2015 USD ($) loan	Dec. 31, 2015 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans over 90 days past due and still accruing interest | loan	0		0		0
Unadvanced commitments on impaired loans	$ 100,000		$ 100,000		$ 0
Specific reserves on restructured loans	1,196,000.000		$ 1,196,000.000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loan			0	0
Unadvanced Commitment on Impaired Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Estimated losses attributable to unadvanced commitments on impaired loans	300,000		$ 300,000		300,000
Non-Covered Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-Modification Outstanding Recorded Balance	$ 2,320,000	$ 0	$ 2,609,000	$ 0
Financing Receivable, Modifications, Number of Contracts | loan	2	0	4	0
Financing Receivable, Gross	$ 2,884,159,000		$ 2,884,159,000		2,750,446,000
Non-Covered Loans | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-Modification Outstanding Recorded Balance	$ 0	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Number of Contracts | loan	0	0	0	0
Financing Receivable, Gross	$ 161,417,000		$ 161,417,000		$ 137,537,000