Derivative Instruments and Hedging Activities (Cash flow hedges of interest rate risk) (Details) - Interest rate swap [Member] - Designated as hedging instrument [Member]	Sep. 09, 2014 USD ($) counterparties
Derivative [Line Items]
Derivative, inception date	Sep. 09, 2014
Derivative agreements, number of counterparties | counterparties	8
Derivative, notional amount | $	$ 400,000,000
Derivative, effective date	Jun. 30, 2015
Derivative, maturity date	May 16, 2019
Derivative, average fixed interest rate	2.02%
London Interbank Offered Rate (LIBOR) [Member]
Derivative [Line Items]
Derivative, variable interest rate	30-day LIBOR