Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
401(k) plan, expense recognized	$ 2.2	$ 2.5	$ 2.9
Contributory health and welfare plan, expense recognized	$ 4.7	$ 6.0	$ 7.0