Segment Reporting Segment Reporting Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) Segment		Dec. 31, 2016 USD ($)		Jun. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | Segment	3
Loans and leases	$ 17,273,678	[1],[2]	$ 17,026,588	[1],[2]	$ 16,272,029
Consumer Portfolio Segment [Member]
Segment Reporting Information [Line Items]
Loans and leases	$ 2,599,318		2,684,500		$ 2,728,452
Consumer Portfolio Segment [Member] | Home Equity Liquidating Portfolio [Member]
Segment Reporting Information [Line Items]
Loans and leases			$ 65,000

[1] At June 30, 2017, the Company had pledged $6.2 billion of eligible residential, consumer and commercial loans as collateral to support borrowing capacity at the FHLB Boston and the FRB of Boston.

[2] Loans and leases include net deferred fees and net premiums/discounts of $18.8 million and $17.3 million at June 30, 2017 and December 31, 2016, respectively.