Liability for Unpaid Claims - Short-Duration Contracts (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 24,341
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	7
2015 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	210
2016 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,174
2017 [Member]
Claims Development [Line Items]
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 17,950