Earnings per Share (Details) (USD $)	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, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount													315,000	90,000	90,000
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per common share (in dollars per share)	$ 0.40	$ 0.35	$ 0.36	$ 0.47	$ 0.50	$ 0.49	$ 0.49	$ 0.43	$ 0.48	$ 0.44	$ 0.57	$ 0.40	$ 1.58	$ 1.91	$ 1.89
Diluted earnings per common share (in dollars per share)	$ 0.40	$ 0.34	$ 0.35	$ 0.45	$ 0.48	$ 0.46	$ 0.47	$ 0.40	$ 0.44	$ 0.41	$ 0.53	$ 0.37	$ 1.53	$ 1.80	$ 1.75
Basic weighted average shares outstanding (in shares)													37,588,000	36,948,000	37,742,000
Diluted weighted average shares outstanding (in shares)													38,642,000	39,100,000	40,889,000
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Basic weighted average shares outstanding (in shares)													37,588,000	36,948,000	37,742,000
Incremental shares for common stock equivalents (in shares)													1,054,000	2,152,000	3,147,000
Diluted shares outstanding (in shares)													38,642,000	39,100,000	40,889,000