Share-Based Compensation (Options) (Details) - Stock options $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Number of Shares
Options outstanding, beginning balance (in shares) | shares	1,186
Options exercised (in shares) | shares	(594)
Options outstanding, ending balance (in shares) | shares	592
Weighted-Average Exercise Price
Options outstanding, beginning balance (usd per share) | $ / shares	$ 20.67
Options exercised (usd per share) | $ / shares	21.28
Options outstanding, ending balance (usd per share) | $ / shares	$ 20.07
Weighted Average Remaining Contractual Term
Options outstanding, Weighted Average Remaining Contractual Term (in years)	3 years 6 months 18 days
Aggregate Intrinsic Value
Options outstanding, Aggregate Intrinsic Value | $	$ 18,829