Collaborative and License Agreements ( Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amgen Inc.
Year of agreement	1996
Number of days to terminate upon written notice to the Company	90
Percentage of Company costs to develop product	0.00%
Nonrefundable license fee received	$ 10.0
Total milestone payments under the agreement payable to the Company	26.0
Future milestone payments outside the Company's control	5.0
Next future milestone payment outside the Company's control	5.0
Total milestone payments paid to the Company to date	21.0
Milestone payments received by the Company	0	0	0
Recognized royalties from product sales received by the Company	111.9	112.9	89.3
Sale of royalty rights	0	0	25.0
GlaxoSmithKline
Year of agreement		2011
Total milestone payments under the agreement payable to the Company	11.5
Future milestone payments outside the Company's control	1.0
Total milestone payments paid to the Company to date	0
Kyowa Hakko Kirin
Year of agreement	1995
Number of days to terminate upon written notice to the Company	90
Percentage of Company costs to develop product	0.00%
Nonrefundable license fee received	5.0
Total milestone payments under the agreement payable to the Company	13.0
Research support payments under the agreement	7.0
Total milestone payments paid to the Company to date	13.0
Research support payments paid to the Company to date	7.0
Milestone payments received by the Company	0	0	0
Recognized royalties from product sales received by the Company	8.5	8.0	8.7
Takeda Teduglutide
Year of agreement	2007
Number of days to terminate upon written notice to the Company	180 or 365
Percentage of Company costs to develop product	50.00%
Nonrefundable license fee received	35.0
Total milestone payments under the agreement payable to the Company	170.0
Total milestone payments payable upon the achievement of certain pre-specified product development milestones	150.0
Total milestone payments payable upon the achievement of certain pre-specified sales-based milestones	20.0
Company payments to licensor to date	6.6
Future milestone payments outside the Company's control	5.0
Total milestone payments paid to the Company to date	40.0
Milestone payments received by the Company	5.0	0	0
Company payments to licensor	2.4
Takeda Preotact
Year of agreement	2004
Number of days to terminate upon written notice to the Company	180
Total milestone payments under the agreement payable to the Company	22.0
Total milestone payments payable upon the achievement of certain pre-specified product development milestones	0.3
Total milestone payments payable upon the achievement of certain pre-specified sales-based milestones	14.5
Future milestone payments outside the Company's control	14.8
Next future milestone payment outside the Company's control	0.3
Total milestone payments paid to the Company to date	7.1
Recognized royalties from product sales received by the Company	9.1	0	4.8
Janssen Pharmaceuticals, Inc.
Year of agreement	2006
Number of days to terminate upon written notice to the Company	60
Percentage of Company costs to develop product	0.00%
Nonrefundable license fee received	8.0
Recognized royalties from product sales received by the Company	2.6	2.9	2.8
Hoffman-La Roche Inc. and F. Hoffmann-La Roche Ltd.
Year of agreement	2008
Number of days to terminate upon written notice to the Company	30
Percentage of Company costs to develop product	0.00%
Nonrefundable license fee received	2.0
Total milestone payments paid to the Company to date	0.3
Milestone payments received by the Company	0.3	0	0
Recognized royalties from product sales received by the Company	0	0	0
In-License and Purchase Agreements
Company maximum royalties to be paid on sales of cinacalcet HCl	15.0
Royalties payable accrued on sales of cinacalcet HCl, to date	15.0
Royalties paid on sales of cinacalcet HCl, to date	10.4
Annual upper limit of royalty payments on sales of cinacalcet HCl	1.0
Royalties recorded in other liabilites on sales of cinacalcet HCl	3.6
Royalties recorded in accrued expenses and other liabilites on sales of cinacalcet HCl	$ 1.0