Share-Based Payment Arrangements (Summary of Option Activity) (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate Intrinsic Value, Outstanding at Beginning | $	$ 3,734
Aggregate Intrinsic Value, Exercised/Released | $	4,065
Aggregate Intrinsic Value, Cancelled/Forfeited | $	$ 6
Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding at Beginning | shares	456,258
Number of Shares, Exercised/Released | shares	(330,644)
Number of Shares, Cancelled/Forfeited | shares	(538)
Number of Shares, Expired | shares	(2,570)
Number of Shares, Outstanding at Ending | shares	122,506
Number of Shares, Exercisable at Ending | shares	122,506
Weighted Average Exercise Price, Outstanding at Beginning | $ / shares	$ 35.91
Weighted Average Exercise Price, Exercised/Released | $ / shares	34.56
Weighted Average Exercise Price, Cancelled/Forfeited | $ / shares	32.09
Weighted Average Exercise Price, Expired | $ / shares	64.74
Weighted Average Exercise Price, Outstanding at Ending | $ / shares	38.98
Weighted Average Exercise Price, Exercisable at Ending | $ / shares	$ 38.98
Weighted Average Remaining Contractual Term (Years), Outstanding at Ending	2 years 9 months 18 days
Weighted Average Remaining Contractual Term (Years), Exercisable at Ending	2 years 9 months 18 days
Aggregate Intrinsic Value, Outstanding at Ending | $	$ 1,507
Aggregate Intrinsic Value, Exercisable at Ending | $	$ 1,507