Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2019 USD ($)
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	$ 9.8
Private equity
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	4.4
Mezzanine debt
Contractual commitments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	$ 5.4