Earnings per Share (Reconciliation Of Number Of Common Shares Used In Calculating Basic And Diluted EPS) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings per Share [Line Items]
Net income	$ 13,721		$ 22,191		$ 19,182		$ 15,487		$ 13,864		$ 18,599		$ 5,080		$ 5,051		$ 70,581	$ 42,594	$ 40,266
Basic weighted-average shares outstanding (in shares)																	40,502,878	40,333,333	40,159,141
Diluted weighted-average shares outstanding (in shares)																	40,709,287	40,553,149	40,382,985
Basic net income per share (in dollars per share)	$ 0.34	[1]	$ 0.55	[1]	$ 0.47	[1]	$ 0.38	[1]	$ 0.34	[1]	$ 0.46	[1]	$ 0.13	[1]	$ 0.13	[1]	$ 1.74	$ 1.06	$ 1.00
Diluted net income per share (in dollars per share)	$ 0.34	[1]	$ 0.54	[1]	$ 0.47	[1]	$ 0.38	[1]	$ 0.34	[1]	$ 0.46	[1]	$ 0.13	[1]	$ 0.13	[1]	$ 1.73	$ 1.05	$ 1.00
Anti-dilutive shares excluded from the calculation (in shares)																	3,441	315	79,267
Performance Shares [Member]
Earnings per Share [Line Items]
Incremental shares (in shares)																	133,766	134,079	146,157
Anti-dilutive shares excluded from the calculation (in shares)																	3,441	0	77,767
Restricted Stock Units (RSUs) [Member]
Earnings per Share [Line Items]
Incremental shares (in shares)																	69,076	70,217	32,455
Anti-dilutive shares excluded from the calculation (in shares)																	0	315	1,500
Stock Options [Member]
Earnings per Share [Line Items]
Incremental shares (in shares)																	3,567	15,520	45,232

[1] 1 Per-share amounts are computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share amounts may not equal the total computed for the year.