Liability for Unpaid Claims - Short-Duration Contracts (Details) $ in Thousands	Jun. 30, 2017 USD ($)
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 21,869
2013 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	0
2014 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	3
2015 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	93
2016 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	2,266
2017 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 19,507