Share-Based Compensation and Capital Stock Narrative (Details) (USD $)	0 Months Ended		3 Months Ended		0 Months Ended		3 Months Ended		0 Months Ended			3 Months Ended													0 Months Ended
	Apr. 16, 2013	Feb. 08, 2013	Mar. 31, 2013	Mar. 31, 2012	Apr. 02, 2013 Subsequent Event [Member]	Apr. 16, 2013 Dividend Paid [Member]	Mar. 31, 2013 Parent [Member]	Mar. 31, 2012 Parent [Member]	Jul. 01, 2013 Scenario, Forecast [Member] Subsequent Event [Member]	Jul. 15, 2013 Scenario, Forecast [Member] Dividend Paid [Member]	Apr. 26, 2013 Scenario, Forecast [Member] Dividend Paid [Member]	Mar. 31, 2013 Stock Options [Member]		Mar. 31, 2012 Stock Options [Member]	Mar. 31, 2013 Performance Vested Restricted Stock Units [Member]		Mar. 31, 2012 Performance Vested Restricted Stock Units [Member]	Mar. 31, 2013 Performance Vested Restricted Stock Units [Member] Minimum [Member]	Mar. 31, 2013 Performance Vested Restricted Stock Units [Member] Maximum [Member]	Mar. 31, 2013 Stock Repurchase Program [Member]	Mar. 31, 2012 Stock Repurchase Program [Member]	Mar. 31, 2013 Minimum Tax Withholding Requirements [Member]	Mar. 31, 2012 Minimum Tax Withholding Requirements [Member]	Mar. 31, 2013 Quarterly [Member]	Aug. 23, 2012 2012 Special Cash Dividend [Member]
Stock options granted												173,413		200,000
Stock options granted, fair value												$ 1,700,000		$ 1,600,000
Aggregate intrinsic value of stock options, outstanding												29,200,000
Aggregate intrinsic value of stock options, exercisable												23,300,000
Total intrinsic value of options exercised												2,300,000		400,000
Proceeds from exercise of stock options			5,367,000	389,000			5,367,000	389,000				5,400,000		400,000
Stock options exercised												204,323		20,216
Stock-based award vesting range percentage																		0.00%	200.00%
Vesting percentage for stock-based award target achievement																		100.00%	160.00%
Grants vested															39,816		0
Grants vested, total fair value															1,300,000
PVRSUs vested, initial grant target															30,624
PVRSU performance percentage target achieved															130.00%
PVRSU increase in shares due to performance percentage target achieved												0	[1]		9,192	[1]
Stock units forfeited															0		0
Cash dividends paid per share						$ 0.185					$ 10,800,000													$ 0.185
Dividends paid			503,000	10,713,000		10,800,000	503,000	10,713,000							500,000		0
Dividends Payable, Date Declared		Feb. 08, 2013
Dividends declared, per share		$ 0.185
Dividends declared but not paid	10,800,000		10,759,000	10,690,000
Dividends Payable, Date to be Paid						Apr. 16, 2013				Jul. 15, 2013															Aug. 23, 2012
Dividends Payable, Date of Record					Apr. 02, 2013				Jul. 01, 2013
Common stock purchased under stock repurchase program, share																				0	300,000
Stock Repurchased During Period, Value																					12,900,000
Common stock redeemed, shares																						96,977	55,162
Common stock redeemed, value																						$ 3,600,000	$ 2,000,000

[1] PVRSU shares have been increased by 9,192 units due to the Company exceeding the targeted performance conditions contained in PVRSUs granted in prior periods during the three months ended March 31, 2013.