Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2018 USD ($)
Contractual commitments to invest in limited partnership investments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	$ 12.2
Private equity
Contractual commitments to invest in limited partnership investments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	4.4
Mezzanine debt
Contractual commitments to invest in limited partnership investments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	7.5
Real estate
Contractual commitments to invest in limited partnership investments
Represents the entity's maximum contractual commitments to invest in its limited partnership investments	$ 0.3