Retirement Savings Plan (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Postemployment Benefits [Abstract]
Percentage of maximum limit for employees to contribute their cash compensation			75.00%
Percentage of employee compensation plus matching contribution			100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			4.00%
Total plan expenses	$ 1.8	$ 0.9	$ 3.9	$ 1.9