Stock-Based Compensation - Summary Of Stock Options Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Stock Options
Outstanding, beginning of year (in shares)	3,782	4,265	6,008
Granted, at fair market value (in shares)	579	734	335
Exercised (in shares)	(1,262)	(1,046)	(1,763)
Expired (in shares)	0	0	0
Forfeited (in shares)	(367)	(171)	(315)
Outstanding, end of year (in shares)	2,732	3,782	4,265
Options exercisable, end of year (in shares)	1,366	2,512	3,385
Weighted Average Exercise Price
Outstanding, beginning of year (in dollars per share)	$ 12.71	$ 9.63	$ 7.26
Granted, at fair market value (in dollars per share)	15.41	19.04	36.05
Exercised (in dollars per share)	5.53	3.72	3.52
Expired (in dollars per share)	0	0	0
Forfeited (in dollars per share)	35.55	17.59	26.26
Outstanding, end of year (in dollars per share)	12.98	12.71	9.63
Options exercisable, end of year (in dollars per share)	$ 7.70	$ 5.85	$ 4.30