Subsequent Events (Details) ft² in Thousands, $ in Millions	3 Months Ended	15 Months Ended
	Sep. 30, 2015 USD ($)	Dec. 31, 2016 USD ($)	Jul. 31, 2015 ft²
New York City [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Area of new headquarters (in sq ft) | ft²			169
New Jersey and New York [Member] | Scenario, Forecast [Member] | Early Termination of Leases [Member]
Subsequent Event [Line Items]
Expected net charges	$ 20.0
Accelerated amortization and depreciation	$ 1.8	$ 5.0