Derivative and Hedging Activities - Narrative (Details)	Mar. 31, 2018 USD ($) Derivatives counterparty	Dec. 31, 2017 USD ($) Derivatives
Derivative [Line Items]
Number of interest rate derivatives held | Derivatives	0	0
Cash collateral balances for derivatives | $	$ 0	$ 0
Expected amount to be transferred of during the next 12 months | $	$ 33,000,000
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, number of instruments held | Derivatives	0	0
Credit Risk [Member]
Derivative [Line Items]
Number of counterparties in hedge facility | counterparty	11