Stockholders' Equity (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended				0 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012	Jul. 15, 2013	May 01, 2014		Oct. 23, 2014	Aug. 30, 2012	Aug. 30, 2011
Class of Stock [Line Items]
Anti-dilutive securities excluded from computation (in shares)	20,768		163,863	249,215
Number of shares repurchased	48,304		13,138	3,419
Number of shares repurchased, average price (in usd per share)	$ 16.53		$ 14.29	$ 14.08
Common stock issued for business combinations	$ 226,235	[1]	$ 24,195	$ 0
Valley Acquisition
Class of Stock [Line Items]
Number of shares issued					1,533,267
Common Stock
Class of Stock [Line Items]
Number of shares issued in conjunction with the merger	14,000,000		1,533,000
Common stock issued for business combinations					24,200	$ 226,200	[1]
Eleventh Plan
Class of Stock [Line Items]
Outstanding share percent								5.00%
Outstanding (in shares)								1,513,000
Tenth Plan
Class of Stock [Line Items]
Outstanding share percent									5.00%
Outstanding (in shares)									757,000
Number of shares the Company will not repurchase									52,025
Ninth Plan
Class of Stock [Line Items]
Outstanding share percent										5.00%
Outstanding (in shares)										782,000

[1] The amount of common stock issued in connection with the merger is net of $489,000 of issuance costs.