Stockholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stockholders' Equity Note [Abstract]
Authorized number of shares to be repurchased (in shares)	15,500,000									15,500,000
Repurchase of treasury stock (in shares)										580,804	479,903
Shares withheld for tax withholding obligations for the vesting of restricted stock awards (in shares)										112,458	116,931
Remaining number of shares authorized to be repurchased (in shares)	768,765									768,765
Payments of Dividends [Abstract]
Dividends declared per share of common stock (in dollars per share)	$ 0.19		$ 0.19	$ 0.19	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.17
Special dividends declared, per share of commong stock (in dollars per share)	$ 2.00
Total regular and special quarterly dIvidend declared, per share of common stock (in dollars per share)	$ 2.19	[1]
Payments of Ordinary Dividends, Common Stock										$ 69,493	$ 17,386	$ 42,728
Special dividend										50,664		25,700
Total Dividends Paid, Ordinary and Special										$ 69,493
Class of Stock [Line Items]
Preferred stock, authorized (in shares)	20,000,000					20,000,000				20,000,000	20,000,000
Common stock purchase right per preferred stock share (in shares)										1
Series A Junior Participating Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, authorized (in shares)	600,000									600,000

[1] 1) Includes a $2.00 per share special dividend