CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock and Additional Paid-In Capital	Retained Earnings	Cumulative Translation Adjustment	Retirement Benefits Adjustment	Cumulative Unrealized Gain (Loss) on Derivatives	Treasury Stock
Balance at Dec. 31, 2013	$ 1,572,989	$ 608,658	$ 1,293,740	$ 52,211	$ (23,857)	$ (31,659)	$ (326,104)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	74,548		74,548
Cumulative translation adjustment	284			284
Pension and other postretirement adjustments (net of tax of $240)	439				439
Amortization of forward starting swaps (net of tax of $663)	1,157					1,157
Issuance of 278,067 shares of common stock from issuance of unvested shares, exercise of stock options and deferred compensation plans (net of tax of $1,875)	9,079	9,079
Repurchase of 551,148 shares of common stock	(40,133)						(40,133)
Shares surrendered for tax withholding	(2,614)						(2,614)
Share-based compensation	5,249	5,249
Balance at Mar. 31, 2014	$ 1,620,998	$ 622,986	$ 1,368,288	$ 52,495	$ (23,418)	$ (30,502)	$ (368,851)