Share-Based Compensation - Schedule of Share Based Compensation Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options, Shares:
Outstanding Beginning Shares	1,833,000	2,063,000	2,736,000
Granted Shares	0	0
Exercised Shares	(581,000)	(7,000)	(653,000)
Forfeited or Expired Shares	(24,000)	(223,000)	(20,000)
Outstanding Ending Shares	1,228,000	1,833,000	2,063,000
Shares Exercisable	1,186,000
Weighted Average Exercise Price:
Outstanding Beginning Weighted Average Exercise Price	$ 23.08	$ 23.03	$ 21.26
Exercised Weighted Average Exercise Price	23.42	18.48	15.63
Forfeited or Expired Weighted Average Exercise Price	26.87	22.75	22.91
Outstanding Ending Weighted Average Exercise Price	22.85	$ 23.08	$ 23.03
Exercisable Weighted Average Exercise Price	$ 22.67
Weighted Average Remaining Contractual Term:
Outstanding Weighted Average Remaining Contractual Term	3 years 1 month 6 days
Exercisable Weighted Average Remaining Contractual Term	3 years 1 month 6 days
Aggregate Intrinsic Value :
Outstanding Aggregate Intrinsic Value	$ 7,298
Exercisable Aggregate Intrinsic Value	$ 7,266