Stock Repurchase Program (Details) (USD $)	0 Months Ended		3 Months Ended		12 Months Ended
	Mar. 08, 2012	May 02, 2011	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Equity, Class of Treasury Stock [Line Items]
Treasury stock value acquired cost method			$ 17,794,000	$ 85,215,000
2011 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program authorized amount	323,700,000	300,000,000
Treasury stock shares acquired			0	2,700,000
Treasury stock value acquired cost method			0	70,000,000
Stock repurchase program remaining authorized repurchase amount			$ 280,000,000		$ 280,000,000