Restructuring - Additional Information (Details) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($) employee
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative				$ 8,455	$ 3,674	$ 11,239
Restructuring liabilities	$ 4,180		$ 3,893	4,180	3,893	6,636
2017 Initiative
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative	$ 3,658			$ 3,658
Number of employees | employee				92
2016 Initiative
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative		$ 4,800	$ 3,700	$ 4,797	$ 3,674
Number of employees | employee					226
2015 Initiative
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring expenses related to restructuring initiative						$ 11,239
Number of employees | employee						208