1.625% Senior Subordinated Convertible Debentures (Notes)	12 Months Ended
Mar. 31, 2016
Senior Subordinated Convertible Debenture Due 2025 [Member]
Debt Instrument [Line Items]
Senior subordinated convertible debentures	1.625% SENIOR SUBORDINATED CONVERTIBLE DEBENTURES In February 2015, the Company issued $1,725.0 million principal amount of 1.625% senior subordinated convertible debentures due February 15, 2025. The debentures are subordinated to the Company's senior debt, including amounts borrowed under its amended credit facility, but are senior to the Company's outstanding 2.125% junior subordinated convertible debentures. The debentures are convertible, subject to certain conditions, into cash, shares of the Company's common stock or a combination thereof, at the Company's election, at an initial base conversion rate of 14.5654 shares of common stock per $1,000 principal amount of debentures, representing an initial base conversion price of approximately $68.66 per share of common stock. As a result of cash dividends paid since the issuance of the debentures, the conversion rate has been adjusted to 15.1396 shares of common stock per $1,000 of principal amount of debentures, representing a base conversion price of approximately $66.05 per share of common stock. In addition, if at the time of conversion the applicable price of the Company's common stock exceeds the base conversion price, the conversion rate will be increased by up to an additional initial base conversion rate of 7.2827 shares of common stock per $1,000 principal amount of debentures, as determined pursuant to a specified formula. As a result of cash dividends paid since the issuance of the debentures, the maximum number of additional shares that may be issued if the stock price of the Company's common stock exceeds the base conversion price has been adjusted to 7.5698 shares of common stock per $1,000 principal amount of debentures. However, in no event will the conversion rate exceed 20.3915 (adjusted to 21.1954 as a result of cash dividends paid since the issuance of the debentures) shares of common stock per $1,000 principal amount of debentures. The Company received net proceeds of approximately $1,694.7 million from the issuance of its senior subordinated convertible debentures after deduction of issuance costs of approximately $30.3 million. The $30.3 million in issuance costs was split between a debt component of $20.4 million and an equity component of $9.9 million. The $20.4 million in debt issuance costs is recorded in other assets and is being amortized using the effective interest method over the term of the debentures. Prior to the close of business on the business day immediately preceding November 15, 2024, the debentures will be convertible at the option of the debenture holders only upon the satisfaction of specified conditions and during certain periods. Thereafter until close of business on the second scheduled trading day immediately preceding February 15, 2025, the debentures will be convertible at the option of the debenture holders at any time regardless of these conditions. Accrued and unpaid interest will be considered fully paid upon settlement of shares. As the debentures can be settled in cash upon conversion, for accounting purposes, the debentures were bifurcated into a liability component and an equity component, which are both initially recorded at fair value. The carrying value of the equity component at March 31, 2016 and March 31, 2015 was $564.9 million. The estimated fair value of the liability component of the debentures at the issuance date was $1,160.1 million resulting in a debt discount of $564.9 million. The unamortized debt discount was $490.3 million at March 31, 2016 and $559.3 million at March 31, 2015. The remaining period over which the unamortized debt discount will be recognized as non-cash interest expense is 8.87 years. In fiscal 2016, the Company recognized $42.6 million in non-cash interest expense related to the amortization of the debt discount compared to $5.7 million in fiscal 2015. The Company recognized $28.0 million of interest expense related to the 1.625% coupon on the debentures in fiscal 2016 compared to $3.8 million in fiscal 2015. The effective interest rate of the debentures is 5.9%.

1.625% SENIOR SUBORDINATED CONVERTIBLE DEBENTURES

In February 2015, the Company issued $1,725.0 million principal amount of 1.625% senior subordinated convertible debentures due February 15, 2025. The debentures are subordinated to the Company's senior debt, including amounts borrowed under its amended credit facility, but are senior to the Company's outstanding 2.125% junior subordinated convertible debentures. The debentures are convertible, subject to certain conditions, into cash, shares of the Company's common stock or a combination thereof, at the Company's election, at an initial base conversion rate of 14.5654 shares of common stock per $1,000 principal amount of debentures, representing an initial base conversion price of approximately $68.66 per share of common stock. As a result of cash dividends paid since the issuance of the debentures, the conversion rate has been adjusted to 15.1396 shares of common stock per $1,000 of principal amount of debentures, representing a base conversion price of approximately $66.05 per share of common stock. In addition, if at the time of conversion the applicable price of the Company's common stock exceeds the base conversion price, the conversion rate will be increased by up to an additional initial base conversion rate of 7.2827 shares of common stock per $1,000 principal amount of debentures, as determined pursuant to a specified formula. As a result of cash dividends paid since the issuance of the debentures, the maximum number of additional shares that may be issued if the stock price of the Company's common stock exceeds the base conversion price has been adjusted to 7.5698 shares of common stock per $1,000 principal amount of debentures. However, in no event will the conversion rate exceed 20.3915 (adjusted to 21.1954 as a result of cash dividends paid since the issuance of the debentures) shares of common stock per $1,000 principal amount of debentures. The Company received net proceeds of approximately $1,694.7 million from the issuance of its senior subordinated convertible debentures after deduction of issuance costs of approximately $30.3 million. The $30.3 million in issuance costs was split between a debt component of $20.4 million and an equity component of $9.9 million. The $20.4 million in debt issuance costs is recorded in other assets and is being amortized using the effective interest method over the term of the debentures.

Prior to the close of business on the business day immediately preceding November 15, 2024, the debentures will be convertible at the option of the debenture holders only upon the satisfaction of specified conditions and during certain periods. Thereafter until close of business on the second scheduled trading day immediately preceding February 15, 2025, the debentures will be convertible at the option of the debenture holders at any time regardless of these conditions. Accrued and unpaid interest will be considered fully paid upon settlement of shares.

As the debentures can be settled in cash upon conversion, for accounting purposes, the debentures were bifurcated into a liability component and an equity component, which are both initially recorded at fair value. The carrying value of the equity component at March 31, 2016 and March 31, 2015 was $564.9 million. The estimated fair value of the liability component of the debentures at the issuance date was $1,160.1 million resulting in a debt discount of $564.9 million. The unamortized debt discount was $490.3 million at March 31, 2016 and $559.3 million at March 31, 2015. The remaining period over which the unamortized debt discount will be recognized as non-cash interest expense is 8.87 years. In fiscal 2016, the Company recognized $42.6 million in non-cash interest expense related to the amortization of the debt discount compared to $5.7 million in fiscal 2015. The Company recognized $28.0 million of interest expense related to the 1.625% coupon on the debentures in fiscal 2016 compared to $3.8 million in fiscal 2015. The effective interest rate of the debentures is 5.9%.