Summary of Operations and Significant Accounting Policies (Earnings Per Share - Diluted) (Details) (USD $) In Thousands, except Per 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 Reconciliation [Abstract]
Weighted average number of common shares outstanding used in computing basic earnings per share									46,363	45,780	45,202
Add: Assumed exercise of stock options and stock awards									1,295	1,119	1,511
Weighted average number of common shares outstanding used in computing diluted earnings per share									47,658	46,899	46,713
Net income attributable to common stockholders	$ 6,204	$ 13,619	$ 8,635	$ (1,926)	$ 4,075	$ 8,553	$ 6,653	$ 4,871	$ 26,532	$ 24,152	$ 50,737
Diluted earnings per share attributable to common stockholders	$ 0.13	$ 0.28	$ 0.18	$ (0.04)	$ 0.09	$ 0.18	$ 0.14	$ 0.10	$ 0.56	$ 0.51	$ 1.09