Derivatives and Hedging Activities Effect of Derivative Instruments on Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2018	Jan. 01, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in OCI on derivatives		$ (9)	$ 175	$ (47)	$ 1,011
Amount of gain or (loss) reclassified from accumulated OCI into income		191	263	502	284
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in OCI on derivatives		(9)	175	(47)	1,011
Interest expense | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) reclassified from accumulated OCI into income		$ 191	$ 263	$ 502	$ 284
Accumulated Net Investment Gain (Loss) Attributable to Parent
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative effect of new accounting principle in period of adoption	[1]						$ 334
ASU 2017-12 | Accumulated Net Investment Gain (Loss) Attributable to Parent
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative effect of new accounting principle in period of adoption						$ 5

[1] Reclassification due to the adoption of ASU 2016-01 and ASU 2017-12. See Part I. Item 1. “Financial Statements and Supplementary Data - Note 15: Recent Accounting Pronouncements.”