Fair-Value Measurements (Narrative) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
7.875% senior unsecured notes (including unamortized premium of $772 and $895 in 2013 and 2012, respectively)	$ 700,772,000	$ 350,895,000
Fair value of debt	732,400,000	373,200,000
Seven Point Eight Seventy Five Percentage Senior Unsecured Notes [Member]
7.875% senior unsecured notes (including unamortized premium of $772 and $895 in 2013 and 2012, respectively)	$ 350,772,000

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_UnsecuredLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant