Benefit Plans - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Employer matching contribution, percent of match		6.00%
Employers matching contribution, vesting percentage		100.00%
Total plan contributions		$ 4,000	$ 3,600	$ 3,200
Plan amendments	$ 3,067	$ 0	$ 0
Recognized Net gain (loss) due curtailments				$ 3,100