Stock-based Compensation Expense Fixed-Price Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares
Outstanding Shares,Beginning Balance (in shares)	1,484,243
Granted (in shares)	313,803	222,939	297,924
Exercised (in shares)	(18,000)
Forfeited (in shares)	(98,519)
Expired (in shares)	(4,600)
Outstanding Shares, Ending Balance (in shares)	1,676,927	1,484,243
Exercisable, Ending Balance (in shares)	998,952
Weighted-Average Exercise Price
Outstanding Weighted-Average Exercise Price, Beginning Balance (in dollars per share)	$ 50.30
Granted (in dollars per share)	55.74
Exercised (in dollars per share)	28.72
Forfeited (in dollars per share)	62.98
Expired (in dollars per share)	66.14
Outstanding Weighted-Average Exercise (in dollars per share)Price, Ending Balance	50.76	$ 50.30
Exercisable Weighted-Average Exercise Price, Ending Balance (in dollars per share)	$ 43.95
Weighted-Average Remaining Contractual Term (Years)
Weighted-Averaged Remaining Contractual Term, Beginning Balance	6 years 1 month 6 days	6 years 6 months
Weighted-Averaged Remaining Contractual Term, Ending Balance	6 years 1 month 6 days	6 years 6 months
Exercisable Weighted-Average Remaining Contractual Term, Ending Balance	4 years 6 months
Aggregate Intrinsic Value
Outstanding Aggregate Intrinsic Value, Beginning Balance	$ 17,887
Outstanding Aggregate Intrinsic Value, Ending Balance	14,152	$ 17,887
Exercisable Aggregate Intrinsic Value, Ending Balance	$ 14,048