Earnings Per Share Earnings Per Share (Narrative) (Details) - Performance-based restricted stock units [Member]	6 Months Ended
Jun. 30, 2017 shares
Minimum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance-based shares available for vesting	0
Maximum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance-based shares available for vesting	456,054

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration