Accumulated Other Comprehensive Income - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Changes in AOCI by component
Beginning balance	$ 40,067	$ 33,457	$ 36,138	$ 29,729
OCI before reclassifications	15,923	(918)	19,908	2,715
Amounts reclassified from AOCI	(9)	88	(65)	183
Net period OCI	15,914	(830)	19,843	2,898
Ending balance	55,981	32,627	55,981	32,627
Effective Portion of Cumulative Loss on Cash Flow Hedges
Changes in AOCI by component
Beginning balance	50	(338)	(26)	(65)
OCI before reclassifications	1	(136)	48	(504)
Amounts reclassified from AOCI	1	88	30	183
Net period OCI	2	(48)	78	(321)
Ending balance	52	(386)	52	(386)
Cumulative Unrealized Gain (Loss) on Available-for-Sale Securities
Changes in AOCI by component
Beginning balance	46,775	33,907	44,929	37,307
OCI before reclassifications	4,917	5,951	6,848	2,551
Amounts reclassified from AOCI	(10)		(95)
Net period OCI	4,907	5,951	6,753	2,551
Ending balance	51,682	39,858	51,682	39,858
Foreign Currency Translation
Changes in AOCI by component
Beginning balance	(6,758)	(112)	(8,765)	(7,513)
OCI before reclassifications	11,005	(6,733)	13,012	668
Net period OCI	11,005	(6,733)	13,012	668
Ending balance	$ 4,247	$ (6,845)	$ 4,247	$ (6,845)

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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