Share-Based Compensation Share-Based Compensation (Summary of Quantitative Effects on Consolidated Financial Statements) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax provision	$ 5,970	$ 7,550	$ 10,281	$ 13,016
Net income	$ 13,794	$ 14,725	$ 24,011	$ 26,276
Basic (usd per share)	$ 0.26	$ 0.28	$ 0.46	$ 0.47
Diluted (usd per share)	$ 0.26	$ 0.27	$ 0.45	$ 0.47
Diluted weighted average shares (in shares)	53,151,134	53,574,702	53,176,425	53,563,676
Change in income taxes			$ 5,430	$ 4,033
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax provision		7,934		14,145
Net income		$ 14,341		$ 25,147
Basic (usd per share)		$ 0.27		$ 0.47
Diluted (usd per share)		$ 0.27		$ 0.47
Diluted weighted average shares (in shares)		53,401,238		53,395,361
Change in income taxes				$ 5,162