Derivative Instruments, Offsetting Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	$ 9,540	$ 9,121
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	9,540	9,121
Gross amounts not offset in the consolidated balance sheet in financial instruments	(9,540)	(9,121)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	0
Interest Rate Swaps [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	8,240	7,639
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	8,240	7,639
Gross amounts not offset in the consolidated balance sheet in financial instruments	(8,240)	(7,639)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	0
Swaptions [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	1,300	1,482
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	1,300	1,482
Gross amounts not offset in the consolidated balance sheet in financial instruments	(1,300)	(1,482)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	$ 0	$ 0