Derivatives (Details) - Summary of net gains (losses) recorded in accumulated other comprehensive income and statements of income relating to cash flow derivative instruments (Interest Rate Contract [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Interest Rate Contract [Member]
Derivatives (Details) - Summary of net gains (losses) recorded in accumulated other comprehensive income and statements of income relating to cash flow derivative instruments [Line Items]
Interest rate contracts	$ (534)