XML 99 R83.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Stock-Based Compensation - Additional Information (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Unrecognized compensation cost related to nonvested share-based compensation arrangements granted | $ | $ 47.5
Period over which cost is expected to be recognized | 2 years 5 months
ESPP |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Percentage payroll deduction that each employee may deduct | 15.00%
Maximum shares (in shares) | 200
Percentage of closing market price paid for purchase of whole shares | 90.00%
Number of shares reserved (in shares) | 1,800,000

X
- Definition Maximum percentage payroll deduction per employee per quarter. + References No definition available. + Details
Name: | bkd_EligibleEmployeeMaximumQuarterlyContributionPercentageAllowed
Namespace Prefix: | bkd_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of closing market price paid for purchase of common stock shares through employee stock purchase plan. + References No definition available. + Details
Name: | bkd_PercentageOfCommonStockClosingMarketPriceToPurchaseWholeShares
Namespace Prefix: | bkd_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of reserved shares held by the Employee Stock Purchase Plan. + References No definition available. + Details
Name: | bkd_SharesHeldInEmployeeStockPurchasePlanReserved
Namespace Prefix: | bkd_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The highest quantity of shares an employee can purchase under the plan per period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PlanNameAxis=bkd_EmployeeStockPurchasePlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |