Share-Based Compensation And Capital Stock Narrative (Details) (USD $)	1 Months Ended									3 Months Ended		9 Months Ended						3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				1 Months Ended
	Nov. 09, 2011	Sep. 30, 2011	Jul. 31, 2011	Apr. 30, 2011	Feb. 28, 2011	Oct. 31, 2010	Jul. 31, 2010	Apr. 30, 2010	Feb. 28, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Performance Vested Restricted Stock Units [Member] Scenario, Forecast [Member]	Sep. 30, 2010 Performance Vested Restricted Stock Units [Member] Scenario, Forecast [Member]	Sep. 30, 2011 Minimum [Member] Performance Vested Restricted Stock Units [Member]	Sep. 30, 2011 Maximum [Member] Performance Vested Restricted Stock Units [Member]	Sep. 30, 2011 Performance Vested Restricted Stock Units [Member]	Sep. 30, 2010 Performance Vested Restricted Stock Units [Member]	Sep. 30, 2011 Performance Vested Restricted Stock Units [Member]	Sep. 30, 2010 Performance Vested Restricted Stock Units [Member]	Sep. 30, 2011 Stock Repurchase Program [Member]	Sep. 30, 2010 Stock Repurchase Program [Member]	Sep. 30, 2011 Stock Repurchase Program [Member]	Sep. 30, 2010 Stock Repurchase Program [Member]	Sep. 30, 2011 Stock Options [Member]	Sep. 30, 2010 Stock Options [Member]	Sep. 30, 2011 Stock Options [Member]	Sep. 30, 2010 Stock Options [Member]	Sep. 30, 2011 Parent [Member]	Sep. 30, 2010 Parent [Member]	Oct. 31, 2011 Dividend Paid [Member]	May 31, 2011 Dividend Paid [Member]
Options granted																										0	0	166,306	300,000
Options granted, fair value																												$ 2,100,000	$ 2,600,000
Aggregate intrinsic value of the stock options, outstanding																										2,300,000		2,300,000
Aggregate intrinsic value of the stock options, exercisable																										1,700,000		1,700,000
Total intrinsic value of options exercised																										200,000	16,000	2,500,000	1,000,000
Stock options exercised																										26,614	600	164,150	66,000
Proceeds from exercise of stock options												3,726,000	1,321,000													600,000	6,000	3,700,000	1,300,000	3,726,000	512,000
Stock-based award vesting range percentage																0.00%	200.00%
Achievement percentage of stock-based award target resulting in zero vesting																				50.00%
Vesting percentage for stock-based award target achievement, minimum																0.00%	100.00%
Remaining stock awards forfeited upon employee termination																				2,442
Grants vested																					10,880
Grants vested																		0		0
Grant date fair value of shares vested																					300,000
Stock units forfeited														39,070	9,650			0	0	41,512	9,650
Cash dividends declared per share					$ 0.185			$ 0.185	$ 0.185	$ 0.185	$ 0.185	$ 0.555	$ 0.555																				$ 0.185
Dividends paid		10,900,000	11,000,000	11,000,000			11,000,000	11,000,000				32,923,000	32,884,000																	32,923,000	32,884,000
Common Stock, Dividends, Per Share, Cash Paid			$ 0.185	$ 0.185		$ 0.185	$ 0.185	$ 0.185																								$ 0.185
Common stock purchased under stock repurchase program, share	700,000																					700,000	50,000	700,000	300,000
Common stock purchased under stock repurchase program, value	23,700,000																					22,200,000	1,900,000	22,200,000	8,700,000
Common stock redeemed, shares																						3,309	1,736	67,336	75,432
Common stock redeemed, value																						$ 100,000	$ 60,000	$ 2,600,000	$ 2,400,000