Stockholders' Equity (Common Stock Shares Activity) (Details)	0 Months Ended	9 Months Ended	12 Months Ended
	Oct. 07, 2013	Dec. 31, 2013	Mar. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock, shares, beginning of period		405,843	333,775
Repurchase of common stock	4,162	168,604	72,068
Treasury stock, shares, end of period		574,447	405,843
Common stock, Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares issued, beginning of period		136,457,444	128,726,324
Issuance of common stock		985,308	1,182,004
Stock options exercised		4,942,435	5,204,890
Share exchange		777,318	1,344,226
Common stock, shares issued, end of period		143,162,505	136,457,444
Non-voting common stock, Class B
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares issued, beginning of period		1,451,600	2,487,125
Share exchange		(508,335)	(1,035,525)
Common stock, shares issued, end of period		943,265	1,451,600
Restricted common stock, Class C
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares issued, beginning of period		1,224,319	1,533,020
Share exchange		(268,983)	(308,701)
Common stock, shares issued, end of period		955,336	1,224,319
Special voting common stock, Class E
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares issued, beginning of period		7,478,522	10,140,067
Stock options exercised		(3,053,708)	(2,661,545)
Common stock, shares issued, end of period		4,424,814	7,478,522