Non-Operating Expense - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Sep. 30, 2014
Debt Instrument [Line Items]
Pretax charge on unamortized financing costs of credit facility and deferred expense on related interest rate swaps		$ 0.4	$ 0.5
Senior unsecured credit facility- revolving loan due 2021
Debt Instrument [Line Items]
Face value		$ 700.0
Debt instrument, maturity year	2021
Senior unsecured credit facility - revolving loan due 2019
Debt Instrument [Line Items]
Face value			$ 700.0